KR20080110619A - Fluid bearing device - Google Patents

Abstract

A fluid bearing device which has excellent moment rigidity and an improved working efficiency in assembling and parts control, and in which a bearing sleeve can be easily manufactured. A plurality of bearing sleeves are axially disposed in the fluid bearing device. The bearing sleeves (3, 4) are so formed that their axial lengths are different from each other. ® KIPO & WIPO 2009

Description

Fluid Bearing Device {FLUID BEARING DEVICE}

The present invention relates to a fluid bearing device.

The fluid bearing device is to rotatably support the shaft member with an oil film formed in the bearing gap. This fluid bearing device has features such as high speed rotation, high speed rotation accuracy, and low noise. In recent years, the fluid bearing device has been developed to take advantage of its characteristics, such as magnetic disk devices such as HDDs, FDDs, CD-ROMs, CD-R / RWs, and DVDs. -Widely used as bearings for spindle motors mounted on optical disk devices such as ROM / RAM, magneto-optical disk devices such as MD, MO, etc., and fan motors mounted on personal computers (PCs), etc. to cool the heat generating source. have.

For example, in a fluid bearing device assembled to a spindle motor of a disk drive device such as an HDD, both a radial bearing part supporting the shaft member in the radial direction and a thrust bearing part supporting in the thrust direction may be constituted by dynamic pressure bearings. . As a radial bearing part in this kind of fluid bearing apparatus, as described in Unexamined-Japanese-Patent No. 2003-239951 (patent document 1), either of the inner peripheral surface of a bearing sleeve and the outer peripheral surface of the shaft member which opposes this, for example. It is known to form a dynamic pressure groove as a dynamic pressure generating portion at the same time, and to form a radial bearing gap between both surfaces.

In a disk drive device such as an HDD, such as an information device incorporating the above-described fluid bearing device, mounting of a plurality of disks is required for the purpose of high capacity, but in this case, the disk drive device acts on a bearing portion that rotatably supports the spindle shaft. The moment load becomes large. In order to cope with the increase in the moment load, it is necessary to provide the radial bearing portions at plural places spaced apart in the axial direction, and to increase the span between the radial bearing portions to increase the moment rigidity. Although the structure which provided these several radial bearing parts in the inner peripheral side of one bearing sleeve is employ | adopted widely, including the said patent document 1, the request of miniaturization of a motor and the miniaturization of the spindle shaft and a bearing sleeve by this is also carried out. In some cases, it may be difficult to manufacture a bearing sleeve that can cope with an increase in span between radial bearing portions.

As a means for increasing the span between radial bearing portions to increase moment rigidity and facilitating the manufacture of bearing sleeves, for example, Japanese Patent Application Laid-Open No. 11-269475 (Patent Document 2) or Japanese Patent No. 3602707 ( As described in patent document 3), the structure which arrange | positions a bearing sleeve in multiple places (for example, two places) of an axial direction is considered. However, in the fluid bearing device having such a configuration, although each bearing sleeve has a different arrangement pattern or formation points of dynamic pressure grooves formed in the inner circumferential surface or the like in consideration of the rotational direction, the axial dimension is formed in the same way so that there is a difference in appearance. It is very smiling. Therefore, there is a problem that the joining direction and the joining position are not easy to be wrong, and the parts management is complicated. If the joining direction or the like is wrong, there is a possibility that the bearing device may not function as a bearing device. Therefore, special consideration is required for the joining, which increases the manufacturing cost of the bearing device.

As another means for improving the moment stiffness, a structure in which the bearing span of the thrust bearing portion is enlarged may be adopted, and as a fluid bearing device having this kind of structure, for example, in JP-A-2005-321089 (Patent Document 4) As disclosed, it is known to form a thrust bearing part at both ends of a bearing sleeve. And the structure which combined the structure of the said patent document 2 (or patent document 3) and patent document 4 in order to improve further moment rigidity can also be employ | adopted. In such a configuration, dynamic pressure generating means such as dynamic pressure grooves for generating fluid dynamic pressure in the thrust bearing gap are often formed on the end face of the bearing sleeve made of sintered metal in consideration of formability, but each dynamic pressure groove is considered in the rotation direction. Therefore, it is necessary to change the inclination direction. Therefore, although two types of bearing sleeves are required, they are formed in substantially the same shape at levels that are difficult to discriminate with the naked eye, and therefore, the joining direction and the joining position tend to be wrong. If the joining direction or the like is wrong, there is a possibility that it will not function as a bearing device as described above. Therefore, special consideration is required for the joining, which increases the manufacturing cost of the bearing device.

By the way, in the structure of the said patent document 2 (or 3), although the bearing span between radial bearing parts can be increased, moment rigidity can be improved and manufacture of a bearing sleeve can be made easy, but the following problem at the time of assembling a bearing apparatus is encountered. It may occur. That is, in this structure, even if each bearing sleeve is formed with high precision, there exists a possibility that a core shift | offset | difference may occur when fixing each bearing sleeve to a housing by means of adhesion | attachment, a press-fitting, etc. The reduction in coaxiality between the two radial bearing surfaces due to core misalignment causes variation in bearing stiffness, which may cause deterioration of bearing performance including moment rigidity.

In addition, the rotational performance of the fluid bearing device is initially determined by the width precision of the bearing gap (for example, the radial bearing gap). Therefore, efforts have been made to accurately form the outer circumferential surface of the shaft member and the inner circumferential surface of the bearing sleeve (bearing member) forming the radial bearing gap. The gap width of the radial bearing gap is often formed uniformly over the axial length as described in, for example, Patent Publication No. 2004-132402 (Patent Document 5).

When assembling to the motor, various rotating bodies are bonded to the shaft member of the fluid bearing device. However, since the size, weight, etc. of the bonded rotating bodies vary depending on the motor, the position of the center of gravity of the rotating bodies is different each time. Therefore, if the clearance width of the radial bearing clearance is formed uniformly over the axial length as described above, the bearing rigidity including the moment rigidity becomes insufficient when vibration or shock is loaded in the fluid bearing device, and the rotation of the rotating body There is a risk of increasing the amount and causing resonance.

In addition, for example, the fluid bearing device assembled to the spindle motor is required to improve not only the moment rigidity as described above but also the rotational accuracy. In order to cope with this, it is necessary to finish the inner circumferential surface of the bearing member and the outer circumferential surface of the shaft member with higher precision, but in general, finishing the inner circumferential surface with high precision is more difficult than finishing the outer circumferential surface with high precision. In addition, there is a limit to increase the processing precision by general machining.

Patent Document 1: Japanese Patent Laid-Open No. 2003-239951

Patent Document 2: Japanese Patent Application Laid-Open No. 11-269475

Patent Document 3: Japanese Patent No. 3602707

Patent Document 4: Japanese Unexamined Patent Publication No. 2005-321089

Patent Document 5: Japanese Patent Application Laid-Open No. 2004-132402

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object thereof is to provide a fluid bearing device which is excellent in moment rigidity, easy to manufacture a bearing sleeve, and which can improve work efficiency of assembly and part management. Is in.

Moreover, the 2nd subject of this invention is providing the fluid bearing apparatus which can avoid the fall of the bearing performance resulting from assembly precision, and can exhibit high moment rigidity as much as possible.

Moreover, the 3rd subject of this invention is providing the fluid bearing apparatus which is excellent in the bearing performance including the moment rigidity, improving the width | variety precision of a radial bearing clearance, and at low cost.

MEANS TO SOLVE THE PROBLEM In order to solve the said 1st subject, in this invention, the radial bearing between the bearing sleeve which has a radial bearing surface, the shaft member inserted in the inner periphery of a bearing sleeve, and the radial bearing surface of a bearing sleeve, and the outer peripheral surface of a shaft member is carried out. In a fluid bearing device having a radial bearing portion for non-contacting support of an axial member in a radial direction by a dynamic pressure action of a fluid generated in a bearing gap, a plurality of bearing sleeves are arranged in an axial direction, and each bearing sleeve is in an axial direction with each other. Provided is a fluid bearing device which is formed with a different length.

According to the said structure, since the bearing sleeve was arrange | positioned in multiple places in the axial direction, the span between radial bearing parts can be enlarged, the load capability with respect to a moment load can be improved, and manufacture of a bearing sleeve can be made easy. In addition, since the axial lengths of the bearing sleeves disposed in the axial direction are different from each other, the difference in appearance becomes clear, and it is possible to reliably prevent assembly errors and to simplify the parts management.

For example, when arranging a bearing sleeve in two places of an axial direction, from the viewpoint which takes a large bearing span of a radial bearing part, the radial bearing surface of one bearing sleeve is in the inner periphery of the end part separated from the other bearing sleeve. It is customary to form. In this case, however, it is particularly difficult to secure coaxial between both ends of the bearing sleeve on the side of which the axial dimension is enlarged and between the bearing sleeves (radial bearing surface), which may adversely affect the rotational performance of the bearing device. have.

Thus, the present invention provides a configuration in which at least one inner circumferential surface of two adjacent bearing sleeves is located on the bearing sleeve side other than the radial bearing surface and has a convex portion having the same diameter as the radial bearing surface. With such a configuration, for example, when the assembling pin is inserted, the assembling work can be easily proceeded while securing coaxially between both ends of the single bearing sleeve and between the bearing sleeves. In addition, since the convex portion is formed in a shape having a dynamic pressure generating function, it causes a torque up, so it is preferable to form a shape having a dynamic pressure generating function (for example, a band shape or the like). However, the convex portion may have a diameter slightly different from that of the radial bearing surface as long as the convex portion can secure the coaxial to the extent that it does not adversely affect the rotational performance. Therefore, the convex part of the same diameter also includes the convex part of a slightly different diameter here.

Also, in the above configuration, a thrust bearing is formed in the shaft member so as to protrude to the outer diameter side, and the thrust bearing non-contactedly supports the shaft member in the thrust direction by the dynamic pressure action of the fluid generated in the thrust bearing clearance between the end face of the protrusion and the end face of the bearing sleeve. You may form a part. The protruding portion may be formed integrally with the shaft member or may be fixed to the shaft member. Moreover, the dynamic pressure generating means, such as a dynamic groove which generate | occur | produces a dynamic pressure action in the thrust bearing clearance of a thrust bearing part, may be formed in at least one of the end surface of a projection part, and the end surface of a bearing sleeve.

Further, the seal space may be formed on the outer circumferential side of the protrusion formed on the shaft member. This seal space has a function of absorbing volume change (expansion and contraction) caused by a temperature change of a fluid (for example, lubricating oil) filled inside the bearing device, a so-called buffer function.

Moreover, as another structure for solving the said 1st subject, in this invention, the rotating member which has a bearing member, the shaft member inserted in the inner periphery of a bearing member, and the 1st and 1st formed between a bearing member and a rotating body A fluid bearing device having a second thrust bearing gap, a first dynamic pressure groove area for generating fluid dynamic pressure in the first thrust bearing gap, and a second dynamic pressure groove area for generating fluid dynamic pressure in the second thrust bearing gap, the bearing comprising: The member has two bearing sleeves arranged in the axial direction, both bearing sleeves having a first dynamic pressure groove region and a second dynamic pressure groove region at both end surfaces, and a first dynamic pressure groove region of one bearing sleeve. Facing the first thrust bearing clearance, and facing the second thrust bearing clearance of the second dynamic pressure groove region of the other bearing sleeve It provides a fluid bearing device according to claim.

As described above, since the bearing member has two bearing sleeves, the bearing span of the radial bearing portion can be increased to increase the moment rigidity, and the manufacturing of the bearing sleeves can be facilitated. In addition, the above-mentioned bearing sleeve has both a 1st dynamic pressure groove area | region and a 2nd dynamic pressure groove area | region in both end surfaces, and makes the 1st dynamic pressure groove area | region of one bearing sleeve face the 1st thrust bearing clearance, and the other The second dynamic pressure groove region of the bearing sleeve faces the second thrust bearing clearance, which means that two identical bearing sleeves are arranged in the axial direction. Therefore, each bearing sleeve can be stuck to a housing, without considering the arrangement of the upper and lower sides, whereby a first thrust bearing clearance is provided at one end side of the bearing member and a second thrust bearing clearance is provided at the other end side, and the moment is further increased. The fluid bearing device excellent in rigidity can be easily formed. In addition, the unit cost can be reduced as much as one type of bearing sleeve can be aggregated, and the management cost of parts can also be reduced.

When the first dynamic pressure groove region and the second dynamic pressure groove region are formed in different shapes, it becomes possible to easily identify the upper and lower sides of each bearing sleeve, and further facilitate the bonding. The term "other shape" herein refers to, for example, a plurality of dynamic pressure grooves arranged in a spiral shape, the other being formed of a plurality of dynamic pressure grooves arranged in a herringbone shape, and the number of grooves of the dynamic pressure grooves arranged in the same shape. It includes both differently. In view of increasing the discrimination, the former configuration is preferable. In addition, when the pressure required in the first thrust bearing gap and the second thrust bearing gap differs depending on the use of the fluid bearing device, the arrangement pattern of the dynamic pressure groove may be changed accordingly.

The spacer member can be interposed between the two bearing sleeves. This spacer member can be formed of a material (non-porous material) having no porous structure, for example, when the bearing sleeve is formed of an oil-containing sintered metal. In this case, since the amount of lubricating oil included in the bearing device can be reduced, the cost can be reduced as the total amount of oil decreases. In addition, as the amount of oil decreases, the volume of the seal space can be reduced, and the bearing span of the radial bearing portion can be further expanded, that is, the moment rigidity can be further increased.

The fluid bearing device having the above structure can be suitably used for the fluid bearing device, the stator coil, the motor having the rotor magnet, and especially the motor requiring particularly high moment rigidity due to the high speed rotation and the weight of the rotating body.

Moreover, in order to solve the said 2nd subject, in this invention, the rotating body which has a bearing member in which the several radial bearing surface is spaced apart in the axial direction, and the shaft member inserted in the inner periphery of a bearing member, A fluid bearing device having a plurality of radial bearing portions for supporting a rotating body in a non-contact manner by the dynamic pressure action of the fluid generated in the radial bearing gap between the radial bearing surface and the outer circumferential surface of the shaft member, wherein the bearing member is in the axial direction. With a plurality of bearing sleeves arranged, all the plurality of radial bearing surfaces are formed in the first bearing sleeve included in the plurality of bearing sleeves, and the first bearing sleeve is located on the side close to the axial center of gravity position of the rotating body. It provides a fluid bearing device, characterized in that arranged. Here, the rotating body refers to the whole rotating object as the spindle of the fluid bearing device, and means an object which is installed on the shaft member and includes all of them if the member is rotatable integrally with the shaft member. For example, when the fluid bearing device is used by assembling a disk drive device such as an HDD, the shaft member, a magnet or disk constituting the drive unit, or a hub (such as a clamper) for installing the magnet or disk on the shaft member or the like is used. Points to an assembly that contains all of them. In addition, when the fluid bearing device is assembled to a fan motor or the like, it refers to an assembly including all of the shaft member, a fan constituting the drive unit, and a fan fixed to the shaft member through a hub or the like.

As described above, the present invention forms all the radial bearing surfaces in one of the bearing sleeves constituting the bearing member, and the axial center of gravity position of the rotating body which supports the bearing sleeves. It is characterized in that placed on the side close to. That is, by condensing all the radial bearing surfaces in one bearing sleeve, the reduction of the coaxial degree resulting from forming radial bearing surfaces in a plurality of bearing sleeves, respectively, and also the fall of bearing rigidity can be avoided. Moreover, compared with the case where coaxial matching is carried out between a some bearing sleeve, work efficiency improves remarkably and this can reduce processing cost. In addition, in this invention, since such a bearing sleeve was arrange | positioned at the side close to the axial center of gravity position of a rotating body, in other words, since it was made to form a radial bearing part in the position close to the axial center of gravity position of a rotating body, it is supported. The rotor can be supported at an appropriate position in accordance with the position of the center of gravity of the rotor to be operated. As a result, the difference between the bearing spans between the radial bearing portions in the case where the radial bearing surfaces are formed separately in the plurality of bearing sleeves can be compensated for, thereby ensuring high moment rigidity.

As a specific structure, the structure in which the 2nd bearing sleeve which does not have a radial bearing surface in the inner periphery of the some bearing sleeve which comprises a bearing member is arrange | positioned at the axial direction one side of a 1st bearing sleeve is mentioned. In this case, the bearing member may have a housing holding a plurality of bearing sleeves on the inner circumference, and the housing may be formed integrally with the second bearing sleeve. Moreover, the bearing member may further have a 3rd bearing sleeve which does not have a radial bearing surface in an inner periphery. In this case, the third bearing sleeve may be disposed on the other side in the axial direction of the first bearing sleeve. Moreover, when a bearing member has a housing which integrally forms a 2nd bearing sleeve, you may arrange | position a 1st bearing sleeve in the axial one side of a 2nd bearing sleeve, and a 3rd bearing sleeve in the axial other side. .

For further improvement of the moment stiffness, for example, a first end face positioned at the one end side in the axial direction among the end faces of the plurality of bearing sleeves constituting the bearing member, and a second end face spaced apart in the axial direction from the first end face, respectively. It may have a configuration in which a thrust bearing surface is formed. According to such a structure, each thrust bearing surface can be formed in the position separated as far as possible in the axial direction of a bearing member. Thereby, the distance in the axial direction of the thrust bearing part formed between the rotating body can be made as large as possible, and the moment rigidity can be further improved.

Moreover, in order to solve the said 3rd subject, in this invention, the fluid which arises in the radial member gap formed between a bearing member, the rotating body which has a shaft member inserted in the inner periphery of a bearing member, and a bearing member and a shaft member. A fluid bearing device comprising a radial bearing portion for supporting a rotating body having an axial member in a radial direction by a membrane, wherein the gap width of the radial bearing gap is changed in the axial direction, and the wide width portion having the large gap width is provided. The narrow bearing part of the narrow part with a small clearance width is arrange | positioned at the center of gravity position of a rotating body, and the area | region which faces at least the radial bearing clearance of a bearing member was formed in the electroforming part which consists of precipitation metals, The fluid bearing characterized by the above-mentioned. Provide the device. In addition, the "rotating body" referred to here refers to the one including both the member installed on the shaft member and rotatable integrally with the shaft member. For example, when assembled to a spindle motor such as an HDD, the rotating body refers to a shaft member, a disk hub provided on the shaft member, a magnet or a disk fixed to the disk hub, and a clamper. In addition, when it is used, for example, when it is assembled to a fan motor, it points out that it contains all the fans, a magnet, etc. which are fixed to the shaft member through a shaft member, a hub, etc.

In general, as the gap width of the radial bearing gap decreases, the rigidity (bearing rigidity) of the fluid film formed in the radial bearing gap increases. Therefore, as described above, if the gap width of the radial bearing gap is changed in the axial direction, and the narrow part among the wide part having the large gap width and the narrow part having the small gap width is arranged at the center of gravity position of the rotating body, The bearing stiffness can be increased near the whole center of gravity, while the bearing stiffness can be lowered in the area away from the center of gravity. As a result, securing of bearing rigidity and lowering torque can be achieved at the same time, and the support accuracy of the rotating body can be improved. Moreover, the separation distance between the bearing center of a radial bearing part and the position of the center of gravity of a rotating body can also be shortened, and moment rigidity can also be improved. The above configuration is such that, for example, the shaft member has a constant diameter in the axial region facing the radial bearing gap and the bearing member has a different diameter, or the shaft member has a different diameter and the bearing member has a different diameter. It can obtain by forming a constant diameter.

The present invention is also characterized in that a region (so-called radial bearing surface) facing at least the radial bearing gap of the bearing member is formed in an electroforming section made of a precipitated metal. The electroforming part can be formed by a method similar to electrolytic plating (electroplating) or electroless plating (chemical plating). Due to the characteristics of this method, the surface on the precipitation start side of the electroforming part becomes a dense surface that is accurately transferred to the level of the micron order to form the surface of the master which forms it. The precision of the inner peripheral surface of the bearing member can be easily increased without performing finishing. Therefore, if the radial bearing surface is formed in the electroforming part, especially the precipitation starting surface, the width accuracy of the radial bearing clearance can be easily increased at low cost. In this configuration, since the radial bearing surface becomes a metal surface, it is possible to suppress changes in the characteristics of the radial bearing surface due to temperature changes and to suppress a decrease in rotational accuracy as much as possible.

In the above configuration, the gap width of the radial bearing gap that can ensure the desired rotational accuracy is the ratio (δ / d) of the minimum diameter gap δ of the radial bearing gap to the shaft diameter d of the shaft member. ), And the present inventors proved that the ratio (δ / d) should be within the range of 1/1000 ≦ δ / d ≦ 1/250. The reason is explained in detail below.

First, the lower limit value 1/1000 of the ratio δ / d can be derived from the roundness, cylinder degree, etc. of the outer circumferential surface of the master or the shaft member and the inner circumferential surface of the electroforming part. In other words, when the diameter gap δ becomes smaller than the roundness and the cylinder degree of the outer circumferential surface of the shaft member or the inner circumferential surface of the bearing member, contact between the shaft member and the bearing member occurs and it becomes difficult to secure a predetermined performance. It is possible to further increase the roundness of the outer circumferential surface of the shaft member and the inner circumferential surface of the bearing member, but it is inevitable that the increase in cost is inevitable. Therefore, in consideration of the balance between the functional and cost aspects, the ratio δ / d is preferably set to 1/1000 or more. In addition, the upper limit 1/250 of ratio (delta / d) can be derived from a rotation precision or a moment rigidity viewpoint. In other words, when the minimum diameter gap δ of the radial bearing gap becomes large, desired bearing rigidity and moment rigidity cannot be secured, resulting in deterioration of rotational accuracy and problems such as contact between the shaft member and the bearing member. Therefore, it is preferable to make ratio (delta / d) into 1/250 or less.

Further, in the above configuration, for example, when the wide width portion is formed at one end of the radial bearing gap and the narrow width portion at the other end, and the gap width is gradually reduced from the wide width portion to the narrow width portion, the axial length of the radial bearing gap is reduced. (L) and the ratio (ε / L) of the decrease amount (ε) of the radial gap in the axial length of the radial bearing gap, in other words, the inclination (ε / L) is 1 / 1000≤ε / L≤1 Preferred to be / 500 has been found by the inventors' earnest research. When the ratio ε / L is smaller than 1/1000, it becomes difficult to sufficiently obtain the above-described improvement of the bearing rigidity and the torque reduction effect. On the other hand, when it is larger than 1/500, the value of the wide part becomes excessive, the bearing rigidity may be insufficient, and the rotational accuracy may deteriorate. In addition, when forming the bearing member, the degree of pulling out the master forcibly increases and the radial bearing surface becomes larger. This is because there is a high risk of causing damage.

In the fluid bearing device described above, a dynamic pressure generating portion for generating a fluid dynamic pressure in the radial bearing gap can be formed, whereby the radial bearing portion can be configured as a dynamic pressure bearing with excellent rotational accuracy. The dynamic pressure generating portion can be formed on the inner circumferential surface of the electroforming portion or the outer circumferential surface of the shaft member. However, the dynamic pressure generating portion can be formed easily and with high precision simply by providing a die portion corresponding to the dynamic pressure generating portion on the master surface used in electroforming. Therefore, it is preferable to form the dynamic pressure generating part on the inner circumferential surface of the electroformed portion, rather than the outer circumferential surface of the shaft member. The dynamic pressure generating portion may adopt various known shapes such as an inclined groove, an axial groove, or an arcuate surface. Moreover, when such dynamic pressure generating part is formed, the area | region facing a dynamic pressure generating part of the clearance gap formed between the inner peripheral surface of a bearing member and the outer peripheral surface of a shaft member turns into a radial bearing clearance referred to here.

Effect of the Invention

As described above, by arranging a plurality of bearing sleeves in the axial direction and forming each bearing sleeve with an axial length different from each other, the moment rigidity is excellent, the bearing sleeves are easy to manufacture, and the work of assembling or managing parts is performed. It is possible to provide a fluid bearing device capable of improving the efficiency.

Further, as described above, the bearing member has two bearing sleeves arranged in the axial direction, and the two bearing sleeves each have a first dynamic pressure groove region and a second dynamic pressure groove region on both end faces, and one bearing By adopting a configuration in which the first dynamic pressure groove region of the sleeve faces the first thrust bearing clearance, and the second dynamic pressure groove region of the other bearing sleeve faces the second thrust bearing clearance, the moment rigidity is excellent, and It is possible to provide a fluid bearing device which is easy to manufacture and which can improve the work efficiency of assembly or parts management.

In addition, as described above, the bearing member is provided with a plurality of bearing sleeves arranged in the axial direction, and all the plurality of radial bearing surfaces are formed in the first bearing sleeve included in the plurality of bearing sleeves, and the first bearing sleeve is further provided. Can be provided on a side close to the axial center of gravity position of the rotating body, whereby a fluid bearing device capable of exerting a high moment rigidity by avoiding a drop in bearing performance due to assembling accuracy as much as possible can be provided.

Further, as described above, the gap width of the radial bearing gap is changed in the axial direction, and the narrow part of the wide part having the large gap width and the narrow part having the small gap width is disposed on the center of gravity position of the rotating body, and the bearing By forming the region facing at least the radial bearing gap of the member in the electroforming part made of the precipitated metal, the width precision of the radial bearing surface can be increased, and a fluid bearing device having excellent bearing performance including moment rigidity can be provided at low cost. .

1 is a cross-sectional view showing a first configuration example of a fluid bearing device according to a first embodiment of the present invention.

2: (A) is a top view which shows the state which fixed the bearing sleeve to the housing, FIG. 2 (B) is sectional drawing, and FIG. 2 (C) is its bottom view.

3: (A) is schematic which shows the assembly process of a bearing sleeve, and FIG. 3 (B) is an expanded sectional view which shows the upper part of a housing.

4 is a cross-sectional view showing a second configuration example of the fluid bearing device according to the first embodiment.

5 is a cross-sectional view conceptually illustrating a spindle motor incorporating a fluid bearing device.

6 is a cross-sectional view conceptually illustrating a fan motor incorporating a fluid bearing device.

7 is a cross-sectional view conceptually illustrating a spindle motor incorporating a fluid bearing device.

It is sectional drawing which shows the 1st structural example of the fluid bearing apparatus which concerns on 2nd Embodiment of this invention.

Fig. 9A is a longitudinal sectional view of the bearing sleeve, Fig. 9B is a view showing the upper end face of the bearing sleeve, and Fig. 9C is a view showing the lower end face of the bearing sleeve.

It is sectional drawing which shows the 2nd structural example of the fluid bearing device which concerns on 2nd Embodiment.

It is a longitudinal cross-sectional view which shows the other structural example of a bearing sleeve.

12 is a cross-sectional view conceptually illustrating a fan motor incorporating a fluid bearing device.

13 is a sectional view conceptually illustrating a spindle motor incorporating a fluid bearing device.

It is sectional drawing which shows the 1st structural example of the fluid bearing apparatus which concerns on 3rd embodiment of this invention.

15 is a sectional view of a bearing member.

FIG. 16 is a cross-sectional view of the bearing member shown in FIG. 15 as viewed in the direction of arrow a. FIG.

It is sectional drawing which looked at the bearing member shown in FIG. 15 in the direction of arrow b.

It is sectional drawing which shows the other structure of a bearing member.

It is sectional drawing which shows the other structure of a bearing member.

It is sectional drawing which shows the 2nd structural example of the fluid bearing device which concerns on 3rd Embodiment.

It is an impregnated sectional drawing which shows the 1st structural example of the fluid bearing device which concerns on 4th Embodiment of this invention.

22 is a cross-sectional view of the bearing member.

FIG. 23 (A) is a perspective view of a master, FIG. 23 (B) is a perspective view which shows the state which masked the master, and FIG. 23 (C) is a perspective view of an electroforming member.

It is sectional drawing of the bearing member immediately after insertion molding.

It is sectional drawing which shows the 2nd structural example of the fluid bearing device which concerns on 4th Embodiment.

It is sectional drawing which shows the 3rd structural example of the fluid bearing device which concerns on 4th Embodiment.

It is sectional drawing which shows the 4th structural example of the fluid bearing device which concerns on 4th Embodiment.

FIG. 28 is a constricted cross sectional view when the radial bearing portion is constituted by a multi-arc bearing. FIG.

Fig. 29 is a constricted cross sectional view when the radial bearing portion is constituted by a multi-arc bearing.

30 is an impregnated cross sectional view when the radial bearing portion is constituted by a multi-arc bearing.

31 is an impregnated cross sectional view when the radial bearing portion is constituted by a step bearing.

(Explanation of symbols for the main parts of the drawing)

1,21: fluid bearing device 2: housing

3: first bearing sleeve 4: second bearing sleeve

5 shaft member 6,7 seal member

8: spacer member A, A ': radial bearing surface

B: Convex portion 11: Axial length of first bearing sleeve

L2: axial length of the second bearing sleeve

P: Assembly pin R1, R2: Radial bearing part

T1, T2: Thrust bearing part S1, S2: Seal space

101: fluid bearing device 102: shaft member

104: stator coil 105: rotor magnet

107 housing 108 bearing member

109,110 seal member 181: bearing sleeve

182: spacer member 81a1, 81b1, 81c1: dynamic pressure groove

R11, R12: radial bearing part T11, T12: thrust bearing part

S11, S12: seal space 201: fluid bearing device

202: rotating body 203: hub

206: shaft member 207,208: seal member

209: bearing member 210: housing

211: first bearing sleeve 212: second bearing sleeve

A21, A22: radial bearing face B21, C21: thrust bearing face

R21, R22: radial bearing part T21, T22: thrust bearing part

301,321,331,341: Fluid Bearing Device

302: rotating body 303: shaft member

304: rotor 305: bearing member

306: electroforming part 307: covering part

308309: radial bearing face 311: master

312: masking part Cr1, Cr2, Cr3: radial bearing clearance

D1: narrow part (of radial bearing clearance)

D2: wide part (of radial bearing clearance)

L: Axial length of radial bearing clearance

R31, R32: radial bearing part T3: thrust bearing part

S3: Seal space d: Shaft diameter of shaft member

EMBODIMENT OF THE INVENTION Hereinafter, the fluid bearing apparatus which concerns on 1st Embodiment of this invention, and the motor provided with this are demonstrated in detail based on FIGS. In addition, the "up-down" direction in the following description merely shows the up-down direction in each figure, and does not limit the installation direction, the use form, etc. of a fluid bearing apparatus. The same applies to other embodiments of the present invention shown in FIG. 7 and later.

1 shows an example of the configuration of a fluid bearing device according to a first embodiment of the present invention. The fluid bearing device 1 shown in the figure supports the rotation of the spindle shaft in the motor assembled to the HDD. The fluid bearing device 1 comprises a housing 2 and a plurality, in this case, two bearing sleeves (first bearing sleeve 3, second bearing sleeve) fixed to the housing 2 at positions axially spaced apart from each other. 4)), a spacer member 8 disposed between the first and second bearing sleeves 3 and 4, and a shaft member 5 inserted into an inner circumference of the first and second bearing sleeves 3 and 4; ) Is provided as a major component.

As described later, the first radial bearing portion R1 is provided between the inner circumferential surface 3a of the first bearing sleeve 3 and the outer circumferential surface 5a of the shaft member 5, and the second bearing sleeve 4 is provided. The second radial bearing portion R2 is provided between the inner circumferential surface 4a and the outer circumferential surface 5a of the shaft member 5. Further, a first thrust bearing portion T1 is provided between the upper end surface 3b of the first bearing sleeve 3 and the lower end surface 6b of the seal member 6, and the lower side of the second bearing sleeve 4 is provided. The second thrust bearing portion T2 is provided between the end surface 4b and the upper end surface 7b of the seal member 7.

The housing 2 is formed into a substantially cylindrical shape by injection molding a resin material, for example, and the first inner circumferential surface 7a on which the first and second bearing sleeves 3 and 4 and the spacer member 8 are fixed is formed of a straight shape. It is formed in a cylindrical surface. In addition, on both ends of the first inner circumferential surface 7a, second and third inner circumferential surfaces 2b and 2c having a diameter larger than the first inner circumferential surface 7a are formed, and the second and third inner circumferential surfaces 2b and 2c are short. It is connected to the 1st inner peripheral surface 2a through the vehicle surfaces 2d and 2e, respectively.

As the base resin used for the resin material for forming the housing 2, any one that can be injection molded can be used regardless of the amorphous resin and the crystalline resin. For example, as the amorphous resin, polysulfone (PSU) and polyether sulfone (PES) can be used. ), Polyphenylsulfone (PPSU), polyetherimide (PEI) and the like, as a crystalline resin liquid crystal polymer (LCP), polyether ether ketone (PEEK), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS) ) And the like can be used. These are of course only examples, and other base resins may be used in consideration of the use environment and the like. The type of the filler to be filled in the base resin is not particularly limited, for example, fibrous fillers such as glass fibers, whisker fillers such as potassium titanate, scaly fillers such as mica, carbon fibers, carbon black, Fibrous or powdery conductive fillers such as graphite, carbon nanomaterial, and metal powder can be used. These fillers may be used independently, or may mix and use 2 or more types.

In addition, the housing 7 can also be formed from soft metal materials, such as brass and an aluminum alloy, and other metal materials.

The shaft member 5 is formed of metal materials, such as stainless steel, and has the shaft shape of substantially the same diameter as a whole. To this shaft member 5, annular seal members 6 and 7 as protrusions are fixed by suitable fixing means such as adhesion or press-fitting (combination of press-fitting and adhesion). These seal members 6 and 7 protrude from the outer peripheral surface 5a of the shaft member 5 to the outer diameter side, and are accommodated in the inner peripheral side of the second and third inner peripheral surfaces 2b and 2c of the housing 2, respectively. do. Further, in order to increase the fixing strength by the adhesive, the circumferential grooves 5a1 and 5a2 serving as the adhesive reservoir are formed on the outer circumferential surface 5a of the shaft member 5 serving as the fixing position of the sealing members 6 and 7. In addition, the sealing members 6 and 7 may be formed from soft metal materials, such as brass (brass), and other metal materials, and may be formed from resin materials. In addition, one of the sealing members 6 and 7 may be integrally formed with the shaft member 5.

The outer circumferential surface 6a of the seal member 6 forms a seal volume S1 of a predetermined volume between the second inner circumferential surface 2b of the housing 2, and the outer circumferential surface 7a of the seal member 7 is a housing. Seal space S2 of predetermined volume is formed between 3rd inner peripheral surface 2c of (2). In this embodiment, the outer circumferential surface 6a of the seal member 6 and the outer circumferential surface 7a of the seal member 7 are each formed in a tapered surface shape which is gradually reduced toward the outer side of the housing 2. Therefore, the seal spaces S1 and S2 exhibit a tapered shape gradually reduced toward the inner side of the housing 2.

The first and second bearing sleeves 3 and 4 are all formed in a cylindrical shape with a porous body made of, for example, a sintered metal, in particular, a porous body made of copper, and each of the first inner circumferential surfaces 2a of the housing 2. ) Is fixed by means such as indentation, adhesion, or indentation bonding. In addition to the sintered metal, the bearing sleeves 3 and 4 may be formed of a metal material such as a copper alloy. The first and second bearing sleeves 3 and 4 are formed with different axial lengths from each other, and in this configuration, the axial length L1 of the first bearing sleeve 3 is equal to that of the second bearing sleeve 4. It is formed larger than the axial length L2 (L1> L2).

As shown in FIG.2 (B), the area | region used as the radial bearing surface A of the 1st radial bearing part R1 is formed in the inner peripheral surface 3a of the 1st bearing sleeve 3, The said radial The bearing surface A is formed with a herringbone-like dynamic pressure groove 3a1. This radial bearing surface A is formed in the edge part of the side (upper side) separated from the 2nd bearing sleeve 4. Moreover, the strip | belt-shaped convex part B is formed in the edge part of the inner peripheral surface 3a of the 1st bearing sleeve 3 on the opposite side (lower side) spaced apart from the radial bearing surface A in the axial direction. This convex part B is formed in substantially the same diameter as the hill part which partitions dynamic pressure groove 3a1.

As shown to FIG. 2 (A), the area | region used as the thrust bearing surface of the 1st thrust bearing part T1 is formed in one part or whole part annular area of the upper end surface 3b of the 1st bearing sleeve 3, The thrust bearing surface is formed with a herringbone-like dynamic pressure groove 3b1. The outer circumferential surface 3d is formed with a plurality of axial grooves 3d1 (three in the illustrated example) arranged at equal intervals in the circumferential direction.

In addition, as shown in FIG. 2 (B), a region serving as the radial bearing surface A 'of the second radial bearing portion R2 is formed on the inner circumferential surface 4a of the second bearing sleeve 4, On the radial bearing surface A ', a herringbone-like dynamic pressure groove 4a1 is formed. In addition, as shown in FIG. 2 (C), a part or the whole part annular region of the lower end surface 4b of the second bearing sleeve 4 is formed with a region serving as a thrust bearing surface of the second thrust bearing portion T2. The thrust bearing surface is formed with a herringbone-like dynamic pressure groove 4b1. Moreover, the outer peripheral surface 4d is formed with the plurality of axial grooves 4d1 (three in the illustrated example) arranged at equal intervals in the circumferential direction.

A cylindrical spacer member 8 formed of a soft metal such as brass or aluminum, a resin material, or a sintered metal is sandwiched between the first and second bearing sleeves 3 and 4, for example, and the 1 is fixed to the inner circumferential surface 2a by means such as press-fitting, bonding, or press-fitting. The inner circumferential surface 8a of the spacer member 8 is formed to have a diameter slightly larger than the inner circumferential surfaces 3a and 4a of both bearing sleeves 3 and 4, and when the shaft member 5 rotates (when bearing operation), the shaft No radial bearing gap is formed between the member 5. The outer peripheral surface 8d is formed with a plurality of axial grooves 8d1 (for example, three) arranged at equal intervals in the circumferential direction.

The fluid bearing device 1 composed of the constituent members is assembled, for example, in the following process.

First, the 1st, 2nd bearing sleeves 3 and 4 and the spacer member 8 are fixed to the 1st inner peripheral surface 2a of the housing | casing 2 in the form shown in FIG. The coaxial securing between both bearing sleeves 3 and 4 at the time of fixation is performed using the assembly pin P as shown, for example in FIG. 3 (A). At this time, since the convex part B of substantially the same diameter as the radial bearing surface A is formed in the inner peripheral surface 3a of the 1st bearing sleeve 3 at the lower end side spaced apart from the radial bearing surface A, The first bearing sleeve 3 is securely coaxially secured between both ends thereof without deteriorating its posture. Moreover, by using this assembly pin P, coaxial securing between the 1st, 2nd bearing sleeves 3 and 4 is reliably performed.

In addition, at the time of fixing both the bearing sleeves 3 and 4 and the spacer member 8 to the housing 2, the upper end surface of the first bearing sleeve 3 is enlarged as shown in FIG. 3 (B). An axial direction of the first bearing sleeve 3 such that 3b is flush with the stepped surface 2d on the upper side of the housing 2 or protrudes from the end face 2d by a few dimensions δ2. It fixes to the inner peripheral surface 2a in the state which adjusted the position. As shown in the figure, when the upper end surface 3b of the first bearing sleeve 3 projects from the end face 2d by the dimension δ2, the lower end face 6b and the end face 2f of the seal member 6 are shown. The axial dimension between) becomes larger than the width b1 of the thrust bearing clearance of the 1st thrust bearing part T1. Although not shown, the second bearing sleeve 4 is also fixed to the first inner circumferential surface 2a of the housing 2 in the same position adjustment as that of the first bearing sleeve 3.

As a result of adjusting the axial position of both bearing sleeves 3 and 4 in the above-described manner and fixing it to the inner circumferential surface 2a of the housing 2, as shown in FIGS. 1 and 2, the first bearing sleeve 3 is There is a slight gap between the lower end face 3c and the upper end face 8b of the spacer member 8, the upper end face 4c of the second bearing sleeve 4 and the lower end face 8c of the spacer member 8. It may occur. In addition, depending on the axial dimension of the first and second bearing sleeves 3 and 4 and the spacer member 8 and the inner circumferential surface 2a of the housing 2, the gap is one of the bearing sleeves 3 and 4. It may occur only on the side. Or both the bearing sleeves 3 and 4 may contact the spacer member 8 in some cases.

Next, the shaft member 5 is inserted into the inner circumferential surfaces 3a and 4a of the first and second bearing sleeves 3 and 4 and the inner circumferential surface 8a of the spacer member 8 to seal members 6 and 7. To the predetermined position of the shaft member (5). In addition, either of the seal members 6 and 7 may be fixed to the shaft member 5 before insertion, or may be integrally formed with the shaft member 5.

After the assembly is completed through the above process, the internal pores of the bearing sleeves 3 and 4 (internal pores of the porous tissue) are also included in the internal space of the housing 2 sealed by the seal members 6 and 7. And lubricating oil, for example, as lubricating fluid. The filling of the lubricating oil can be performed, for example, by immersing the fluid bearing device 1 having completed assembly in the lubricating oil in a vacuum chamber and then opening it to atmospheric pressure.

When the shaft member 5 rotates in the fluid bearing device 1 having the above configuration, the radial bearing surface A of the inner circumferential surface 3a of the first bearing sleeve 3 is the outer circumferential surface 5a of the shaft member 5. ) And through the radial bearing clearance. On the radial bearing surface A, the lubricating oil filled in the radial bearing gap increases its pressure due to the dynamic pressure action of the dynamic pressure groove 3a1, and by this pressure, the shaft member 2 is rotatably contacted in the radial direction. Supported. In this configuration example, a radial bearing gap is formed between the convex portion B and the outer circumferential surface 5a of the shaft member 5, and the radial bearing gap is provided with oil extruded from the first bearing sleeve 3. An oil film is formed, and the oil film is rotatably supported by the shaft member 5 in the radial direction. Thereby, the 1st radial bearing part R1 which supports the shaft member 5 rotatably in the radial direction by the dynamic bearing and the cylindrical bearing is comprised. In the second bearing sleeve 4, the dynamic bearing is also constituted by the radial bearing surface A ', and the second radial bearing portion R2 for rotatably supporting the shaft member 5 in the radial direction is constituted. do.

Further, when the shaft member 5 rotates, the thrust bearing surface of the upper end surface 3b of the first bearing sleeve 3 faces the lower end surface 6b of the seal member 6 through a predetermined thrust bearing gap. The thrust bearing surface of the lower end surface 4b of the second bearing sleeve 4 opposes the upper end surface 7b of the seal member 7 through a predetermined thrust bearing gap. The lubricating oil filled in each of the thrust bearing gaps with the rotation of the shaft member 2 has a high pressure due to the dynamic pressure action of the dynamic grooves 3b1 and 4b1, and the shaft member 5 is non-contactably rotatable in both thrust directions. Supported. Thereby, the 1st thrust bearing part T1 and the 2nd thrust bearing part T2 which rotatably support the shaft member 5 rotatably in both thrust directions are formed.

In the rotation of the shaft member 5, as described above, the seal spaces S1 and S2 formed on the outer circumferential surface 6a side of the seal member 6 and the outer circumferential surface 7a side of the seal member 7 are housed. Since the taper shape is gradually reduced toward the inner side of (2), the lubricating oil in both seal spaces S1 and S2 has a narrow seal space due to a capillary force pull-in action and a centrifugal force pull-in action. It is pulled in the direction of loss, ie towards the inner side of the housing 2. As a result, leakage of lubricant oil from the inside of the housing 2 is effectively prevented. In addition, the seal spaces S1 and S2 have a buffer function for absorbing the volume change amount according to the temperature change of the lubricating oil filled in the internal space of the housing 2, and the oil surface of the lubricating oil is within the range of the assumed temperature change. It is always in the seal spaces S1 and S2.

Further, the fluid passage formed by the axial groove 3d1 of the first bearing sleeve 3, the fluid passage formed by the axial groove 4d1 of the second bearing sleeve 4, the spacer member 8 of the Fluid passage formed by the axial groove 8d1, each bearing gap (radial bearing gap between the first radial bearing portion R1 and the second radial bearing portion R2, the first thrust bearing portion T1) And a thrust bearing gap of the second thrust bearing portion T2, and a gap between the inner circumferential surface 8a of the spacer member 8 and the outer circumferential surface 5a of the shaft member 5 in series. The circulation passage of is formed. As the lubricant filled in the internal space of the housing 2 flows through this circulation passage, the pressure balance of the lubricant is maintained, and at the same time, the generation of the lubricant due to the generation of bubbles and the generation of bubbles due to the local negative pressure is generated. Leakage or vibration is prevented. In addition, one end of the fluid passage formed by the axial groove 3d1 of the first bearing sleeve 3 and one end of the fluid passage formed by the axial groove 4d1 of the second bearing sleeve 4 are respectively. It communicates with the seal spaces S1 and S2 used as the air opening side. Therefore, even if bubbles are mixed in the lubricant for some reason, the bubbles are discharged to the outside air opening side when circulating along the lubricant, so that adverse effects caused by the bubbles are more effectively prevented.

In addition, although not shown, the axial fluid passage formed between the two bearing sleeves 3 and 4 and the spacer member 8 and the housing 2 has an axial groove in the inner circumferential surface 2a of the housing 2. You may form by forming.

In the above configuration, since the axial span between the radial bearing portions R1 and R2 can be increased, the load capacity for the moment load can be increased, and the extension of the individual bearing sleeves can be prevented. Bearing sleeves 3 and 4 with high precision can be easily manufactured. In addition, since the axial lengths of the first bearing sleeve 3 and the second bearing sleeve 4 are different from each other, apparent differences in appearance can be reliably prevented, and assembly errors can be reliably prevented, and parts management can be simplified. can do.

Moreover, in this structural example, it is the same as a radial bearing surface A in the axial lower end part spaced apart from the radial bearing surface A among the inner peripheral surfaces 3a of the 1st bearing sleeve 3 which enlarged the axial length. Since the convex part B of diameter was formed, it can reliably secure coaxial between radial bearing surfaces A and A 'at the time of assembly, and can prevent the fall of bearing performance by this kind of precision fall. have. In addition, although the case where the convex part B was formed in continuous strip shape over the whole circumference of the inner peripheral surface 3a was demonstrated, if convex part B can be reliably ensured, the convex part B may be performed reliably. ) May be formed intermittently in the circumferential direction, for example.

4 shows another configuration example (second configuration example) of the fluid bearing device according to the first embodiment of the present invention. The main point that the fluid bearing device 21 shown in the figure differs from the fluid bearing device 1 described above is that the inner circumferential surface 2a of the housing 2 extends to the end face of the housing 2 with a uniform diameter. Therefore, the sealing members 6 and 7 have a relatively small diameter. In such a configuration, there is an advantage that the shape of the housing 2 can be simplified and small in size as compared with the fluid bearing device 1 of the first configuration example. In this configuration example, the lower end surface 3c of the bearing sleeve 3 and the upper end surface 2c2 of the spacer portion 2c are in contact with each other, and the upper end surface 4c and the spacer portion 2c of the bearing sleeve 4 are in contact with each other. The lower end surface 2c3 of is in contact. Other matters are based on the first configuration example, and therefore, common reference numerals are used to omit duplicate explanation.

In the above description, the herringbone-shaped dynamic pressure grooves are exemplified as the dynamic pressure generating means of the radial bearing portions R1 and R2 and the thrust bearing portions T1 and T2, but may be spiral or other dynamic pressure grooves. Alternatively, a so-called step bearing or a circular arc bearing may be employed as the dynamic pressure generating means.

FIG. 5 conceptually shows one configuration example of a spindle motor for information apparatus in which the fluid bearing device 1 shown in FIG. 1 is assembled among the fluid bearing devices according to the first embodiment of the present invention. This spindle motor is used in, for example, a server HDD, and includes a fluid bearing device 1, a rotor (disk hub 12) mounted on a shaft member 5 of the fluid bearing device 1, and a radial direction (lady). And a stator coil 10 and a rotor magnet 11 which face each other with a gap in the direction thereof. The stator coil 10 is attached to the outer circumference of the bracket 9, and the rotor magnet 11 is attached to the inner circumference of the disc hub 12. The housing 2 of the fluid bearing device 1 is mounted on the inner circumference of the bracket 9. The disk hub 12 holds one or more disks D such as a magnetic disk. When the stator coil 10 is energized, the rotor magnet 11 rotates by the electromagnetic force between the stator coil 10 and the rotor magnet 11, whereby the disc hub 12 and the disc hub 12 are rotated. The disk D held at the shaft rotates integrally with the shaft member 5.

The fluid bearing device described above is not limited to a spindle motor for a disk device such as an HDD, but can also be preferably used for a motor such as a fan motor that rotates at high speed and requires a load capacity for high moment load.

FIG. 6 shows a fan motor incorporating a fluid bearing device 1 according to a first embodiment of the present invention, among which a stator coil 10 and a rotor magnet 11 with gaps in a radial (radial direction) interposed therebetween. This example conceptually illustrates an example of a so-called radial gap fan motor in which? The motor of the example is mainly characterized in that the rotor 13 fixed to the upper outer circumference of the shaft member 5 has a wing on its outer circumference, and the bracket 9 functions as a casing for accommodating each component of the motor. The configuration differs from the spindle motor shown in FIG. 5. In addition, since other matters conform to the spindle motor shown in FIG. 5, a common reference number is attached | subjected and the duplication description is abbreviate | omitted.

EMBODIMENT OF THE INVENTION Hereinafter, the fluid bearing apparatus which concerns on 2nd Embodiment of this invention, and the motor provided with this are demonstrated based on FIGS. 7-12.

Fig. 7 conceptually shows one configuration example of a spindle motor for information apparatus incorporating a fluid bearing device according to a second embodiment of the present invention. This spindle motor is used for a disk drive device such as an HDD. The spindle motor includes a fluid bearing device 101, a rotor (disk hub 103) attached to the shaft member 102, and a radial gap between them. A stator coil 104 and a rotor magnet 105 which face each other are provided. The stator coil 104 is attached to the outer circumference of the bracket 106, and the rotor magnet 105 is attached to the inner circumference of the disc hub 103. The housing 107 of the fluid bearing device 1 is mounted on the inner circumference of the bracket 106. The disk hub 103 holds one or a plurality of disks D11, such as a magnetic disk. When the stator coil 104 is energized, the rotor magnet 105 rotates by the electromagnetic force between the stator coil 104 and the rotor magnet 105, whereby the disk hub 103 and the disk hub 103 are rotated. The disk D11 held at the shaft rotates integrally with the shaft member 102.

8 shows an example of the configuration of a fluid bearing device according to a second embodiment of the present invention. This fluid bearing device 101 includes, as a main component, a rotating member on the rotating side having a bearing member 108 on the fixed side and a shaft member 102 inserted into the inner circumference of the bearing member 108. In this structural example, the rotating body is comprised from the sealing member 109,110 provided so that the shaft member 102 and the shaft member 102 may be spaced apart in two axial directions. In this configuration, the bearing member 108 includes two bearing sleeves 181 and 181 spaced apart from each other in the axial direction, a spacer member 182 sandwiched between the two bearing sleeves 181 and 181, and both bearing sleeves. 181 and 181 and the spacer member 182 are comprised by the housing 107 which fixed the inner periphery.

In the fluid bearing apparatus 101 shown in FIG. 8, as described later, the first radial bearing portion R11 is provided between the inner circumferential surface 181a of the upper bearing sleeve 181 and the outer circumferential surface 102a of the shaft member 102. ) Is provided, and a second radial bearing portion R12 is provided between the inner circumferential surface 181a of the lower bearing sleeve 181 and the outer circumferential surface 102a of the shaft member 102. Further, the first thrust bearing portion T11 is provided between the upper end surface 181b of the upper bearing sleeve 181 and the lower end surface 109b of the seal member 109, and the lower side of the lower bearing sleeve 181 is provided. The second thrust bearing portion T12 is provided between the end surface 181c and the upper end surface 110b of the seal member 110.

The shaft member 102 is formed of a metal material such as stainless steel. The shaft member 102 has a shaft shape of approximately the same diameter as a whole, and an intermediate portion 102b is formed with a diameter slightly smaller than other locations. A recess, for example, a circumferential groove 102c, is formed in the fixing position of the seal members 109 and 110 in the outer circumferential surface 102a of the shaft member 102. In addition, in this embodiment, although the shaft member 102 is an integral processed product of metal, it can also be set as the hybrid shaft (a sheath part is a metal, and a core part is resin) in which metal consists of resin.

The housing 107 has a cylindrical shape with openings at both ends, and the inner circumferential surface 107a is formed as a straight cylindrical surface with a constant diameter in the axial direction. The housing 107 is, for example, a machined product of a metal material such as brass or aluminum, or an injection molded product of a resin composition. In the case of injection molding into a resin composition, the base resin that can be used is not particularly limited, but, for example, amorphous such as polysulfone (PSU), polyethersulfone (PES), polyphenylsulfone (PPSU), polyetherimide (PEI), etc. In addition to the resin, crystalline resins such as liquid crystal polymer (LCP), polyether ether ketone (PEEK), polybutylene terephthalate (PBT) and polyphenylene sulfide (PPS) can be used. The type of the filler to be filled in the resin is not particularly limited, for example, fibrous fillers such as glass fibers, whisker fillers such as potassium titanate, scaly fillers such as mica, carbon fibers, carbon black, Fibrous or powdery conductive fillers such as graphite, carbon nanomaterials, and metal powders can be used. These fillers may be used independently, or may mix and use 2 or more types.

The two bearing sleeves 181 and 181 are both formed in a cylindrical shape with a porous body made of a sintered metal, in particular, a porous body made of copper with a main component thereof. Both bearing sleeves 181 and 181 may be formed of a soft metal such as brass. In the outer peripheral surface 181d of the bearing sleeve 181, axial grooves 181d1 are formed at plural places in the circumferential direction (three places in the illustrated example) at equal intervals.

In the inner circumferential surface 181a of both bearing sleeves 181 and 181, a region serving as the radial bearing surface A11 of the first and second radial bearing portions R11 and R12 is formed, respectively, and the radial bearing surface A11 is formed. 9A, for example, a plurality of dynamic pressure grooves 181a1 arranged in a herringbone shape are formed in an symmetrical shape in the axial direction. The dynamic pressure grooves 181a1 may be arranged in an unknown shape such as a spiral shape.

A first dynamic pressure groove made up of a plurality of dynamic pressure grooves 181b1 arranged in a spiral shape in a part or the whole annular region of the upper end surface 181b of both bearing sleeves 181 and 181, for example, as shown in Fig. 9B. The area is formed. In addition, a second dynamic pressure groove region including a plurality of dynamic pressure grooves 181c1 arranged in a herringbone shape is formed in a part or the whole annular region of the lower end surface 181c, for example, as shown in Fig. 9C. . In this embodiment, the 1st dynamic pressure groove area | region of the upper bearing sleeve 181 becomes the thrust bearing surface B11 of the 1st thrust bearing part T11, and the 2nd dynamic pressure groove area | region of the lower bearing sleeve 181 is It becomes the thrust bearing surface C11 of the 2nd thrust bearing part T12. The above-mentioned dynamic pressure grooves 181a1, 181b1, and 181c1 can all be formed simultaneously with the molding of the bearing sleeve 181.

A cylindrical spacer member 182 is sandwiched between two bearing sleeves 181, 181. The spacer member 182 is formed of a metal material such as brass or aluminum, or a resin material, and the inner circumferential surface 182a is formed to have a diameter larger than the inner circumferential surface 181a of the bearing sleeve 181. In the present embodiment, the spacer member 182 has the upper end surface 182b of the lower end surface 181c of the upper bearing sleeve 181 and the lower end surface 182c of the upper end surface of the lower bearing sleeve 181. It is arrange | positioned at the substantially axial direction center part of the inner periphery of the housing 107 in contact with 181b. In the outer peripheral surface 82d of the spacer member 182, axial grooves 182d1 are formed in plural places (for example, three places) in the circumferential direction.

The seal members 109 and 110 are all formed in a ring shape with a soft metal material such as brass, other metal materials, or a resin material, and are for example adhesively fixed to the outer peripheral surface 102a of the shaft member 102. The adhesive applied to the member 102 is filled and solidified in the circumferential groove 102c as the adhesive reservoir, thereby improving the adhesive strength of the seal members 109 and 110 to the shaft member 102.

The outer circumferential surface 109a of the seal member 109 forms the first seal space S11 of a predetermined volume between the inner circumferential surface 107a of the upper opening side of the housing 107, and also the outer circumferential surface of the seal member 110. 110a forms the 2nd seal space S12 of predetermined volume between the inner peripheral surface 107a of the lower end opening side of the housing 107. As shown in FIG. In this configuration example, the outer circumferential surface 109a of the seal member 109 and the outer circumferential surface 110a of the seal member 110 are each formed in a tapered surface shape gradually reduced toward the outer side of the bearing device. Therefore, both seal spaces S11 and S12 become a tapered shape gradually reduced in the direction approaching each other (inner direction of the housing 107). When the shaft member 102 rotates, the lubricating oil in both seal spaces S11 and S12 is drawn in the capillary force and in the direction in which the seal space is narrowed by the pull action by the centrifugal force during rotation (in the housing 107). Inward). As a result, leakage of lubricant oil from the inside of the housing 107 is effectively prevented. In order to reliably prevent oil leakage, the upper and lower end faces of the housing 107, the upper end face 109c of the seal member 109, and the lower end face 110c of the seal member 110 are respectively oil-repellent agents. It is also possible to form a film formed (not shown).

The first and second seal spaces S11 and S12 have a buffer function for absorbing the volume change amount according to the temperature change of the lubricating oil filled in the internal space of the housing 107. Within the range of assumed temperature changes, the oil surface is always in both seal spaces S11 and S12. To realize this, the total sum of the volumes of the two seal spaces S11 and S12 is set larger than the volume change due to the temperature change of the lubricating oil filled in at least the internal space.

Assembly of the fluid bearing apparatus 101 which consists of the said structure is performed as follows, for example.

The bearing sleeves 181 and 181 and the spacer member 182 are fixed to the inner circumferential surface 107a of the housing 107 by appropriate means such as adhesion, press fitting and welding. Then, after the shaft member 102 is inserted into the inner circumferences of the bearing sleeves 181 and 181 and the spacer member 182, the seal members 109 and 110 are provided with a predetermined axial gap so as to sandwich the bearing sleeves 181 and 181 and the spacer member 182. Adhesively fixed to the outer circumference of the circumferential groove (102c) of the shaft member 102 in the secure state. In this way, when the assembly of the fluid bearing device 101 is completed, the internal pores of both bearing sleeves 181 and 181 are also included in the internal space of the housing 107 sealed by both seal members 109 and 110, and as a lubricating fluid. For example, it is filled with lubricating oil. The filling of the lubricating oil can be performed, for example, by immersing the fluid bearing device 101 having completed assembly in the lubricating oil in a vacuum chamber, and then opening it to atmospheric pressure.

When the shaft member 102 rotates in the fluid bearing device 101 having the above-described configuration, the radial bearing surfaces A11 of the inner circumferential surface 181a of both bearing sleeves 181 are respectively the outer circumferential surface 102a of the shaft member 102. ) And through the radial bearing clearance. As the shaft member 102 rotates, dynamic pressure of lubricating oil is generated in each radial bearing gap, and the shaft member 102 is rotatably supported in a non-contact manner by the pressure. As a result, the first radial bearing portion R1 and the second radial bearing portion R2 are formed to rotatably support the shaft member 102 in the radial direction.

Moreover, when the shaft member 102 rotates, the area | region (first dynamic pressure groove area | region) which becomes the thrust bearing surface B11 of the upper end surface 181b of the upper bearing sleeve 181, the lower end surface of the sealing member 109 An area (second dynamic pressure groove region) which faces 109b and a thrust bearing surface C11 of the lower end surface 181c of the lower bearing sleeve 181 and faces through a predetermined first thrust bearing gap is sealed. The upper end surface 110b of 110 is opposed through a predetermined second thrust bearing gap. As the shaft member 102 rotates, dynamic pressure of lubricating oil is generated in each of the thrust bearing gaps, and the pressure prevents the shaft member 102 from being rotatably supported in both thrust directions. Thereby, the 1st thrust bearing part T11 and the 2nd thrust bearing part T12 which rotatably support the axial member 102 rotatably in both thrust directions are formed.

By the way, during operation of the fluid bearing apparatus 101, the generation of bubbles due to the local negative pressure, the leakage of lubricating oil due to the generation of bubbles, the generation of vibration, etc. may occur. In contrast, in the present embodiment, the axial grooves 181d1 of both bearing sleeves 181 and 181, the axial grooves 182d1 of the spacer member 182, and the respective bearing clearances (first and second radial bearing portions R11, Between the radial bearing clearance of R12, the thrust bearing clearance of the first and second thrust bearing portions T11, T12, and the inner circumferential surface 182a of the spacer member 182 and the outer circumferential surface 102a of the shaft member 102; Since a series of circulation flow paths were formed inside the fluid bearing device 101 by the gap of, the lubricating oil flows and flows through this circulation flow path during the bearing operation. By this, the problem is effectively prevented. Further, one end of the axial grooves 181d1 of the two bearing sleeves 181 communicates with the seal spaces S11 and S12 serving as the atmospheric opening sides, respectively. Therefore, even when bubbles are mixed in the lubricant for some reason, the bubbles are discharged to the outside air opening side when the bubbles are circulated along the lubricant, so that adverse effects caused by the bubbles are more effectively prevented.

In the above-described configuration, the bearing sleeves 181 and 181 each have a first dynamic pressure groove region including the dynamic groove 181b1 on the upper end surface 181b and a second dynamic pressure groove region including the dynamic groove 181c1 on the lower end surface 181c. In other words, the bearing member 108 is formed using two identical bearing sleeves. Accordingly, the bearing sleeves 181 and 181 can be stuck to the housing 107 without considering the upper and lower positional relationship, and the bearing member 108 while avoiding the problem that the fluid bearing device 101 cannot be used due to assembly error. The thrust bearing portions T11 and T12 are provided on both ends of the c) so that the fluid bearing device 101 having excellent moment rigidity can be obtained easily and at low cost. In particular, in this configuration example, the dynamic pressure grooves 181b1 of the upper end surface 181b are arranged in a spiral shape to form a first dynamic pressure groove region, and the dynamic pressure grooves 181c1 of the lower end surface 181c are arranged in a herringbone shape. Since the two dynamic pressure groove regions are formed, it is possible to increase the discrimination of both end faces and to reliably prevent the situation of joining the upper and lower parts of each bearing sleeve 181 by mistake.

In addition, since the two types of bearing sleeves can be aggregated into one type of bearing sleeve, the unit cost can be reduced and the management cost of the parts can be reduced.

Moreover, in this structural example, the dynamic pressure groove arrange | positioned in the spiral shape is formed in the thrust bearing surface B11 (first dynamic pressure groove area | region) which faces the 1st thrust bearing clearance of the 1st thrust bearing part T11, and the 2nd Although the thrust bearing surface C11 (second dynamic pressure groove region) facing the second thrust bearing clearance of the thrust bearing portion T12 is formed with a dynamic pressure groove arranged in a herringbone shape, for example, if identification can be ensured, The first dynamic pressure groove region and the second dynamic pressure groove region may be configured as dynamic pressure grooves arranged in the same shape with different numbers of grooves or inclination angles.

In addition, in the above, the arrangement shape of the dynamic pressure groove of the 1st dynamic pressure groove area | region and the 2nd dynamic pressure groove area | region was focused only on identification, but it is necessary in the 1st thrust bearing part T11 and the 2nd thrust bearing part T12, for example. Depending on the pressure, the arrangement shape and the number of grooves may be different.

In this configuration example, since the spacer member 182 of the non-porous body is sandwiched between the bearing sleeves 181 and 181, the amount of lubricating oil to be filled inside the bearing can be reduced. Thereby, the axial dimension of the sealing members 109 and 110 can be shortened, and the bearing span of radial bearing parts R11 and R12 can be enlarged.

In addition, although illustration is abbreviate | omitted, in the fluid bearing apparatus 101 of the said structure, either of the sealing members 109 and 110 can be formed integrally with the shaft member 102, and by setting it as this structure, the fluid bearing apparatus 101 You can simplify the pasting of.

In addition, although the above description demonstrated the case where the dynamic pressure generating means (dynamic pressure groove) which generate | occur | produces fluid dynamic pressure in a radial bearing clearance gap is formed in the inner periphery of the bearing sleeve 181, dynamic pressure groove | channel is provided through a radial bearing clearance. You may form in the outer peripheral surface 102a of the opposing shaft member 102. FIG. In this case, since the upper and lower positional relationship of both bearing sleeves does not affect the rotational performance, the dynamic pressure groove for forming the first radial bearing portion R1 and the dynamic pressure groove for forming the second radial bearing portion R2 are provided. May have different shapes or the like.

10 shows another configuration example (second configuration example) of the fluid bearing device according to the second embodiment of the present invention. The fluid bearing device 121 shown in the same drawing is different from the fluid bearing device 101 shown in FIG. 8 in that the bearing member 108 mainly consists of two bearing sleeves 181 and 181 and the housing 7. At this time, in the case where the dynamic groove is formed in the inner circumferential surface 181a of the bearing sleeve 181, when the dynamic groove 181a2 has the shape of a plurality of axial grooves formed at equal intervals in the circumferential direction as shown in FIG. 8, the bonding can be performed without considering the vertical position of both bearing sleeves 181, 181. The radial bearing portions R11 and R12 constituted by the dynamic pressure grooves 181a2 of this form are so-called step bearings. Of course, when the dynamic pressure groove for forming the radial bearing portions R11 and R12 is formed on the outer circumferential surface 102a of the shaft member 102, the shape can be freely set as described above. In addition, since a structure other than this is based on the 1st structural example shown in FIG. 8, a common reference number is attached | subjected and overlapping description is abbreviate | omitted.

In the fluid bearing apparatuses 101 and 121 described above, the radial bearing portions R11 and R12 can also be configured as so-called multi-circular bearings in which a plurality of circular arc surfaces are formed in a region serving as the radial bearing surface. The thrust bearing portions T11 and T12 have a plurality of radial grooves defined in the circumferential direction in the region serving as the thrust bearing surface, in addition to generating dynamic pressure action of the lubricating oil by dynamic pressure grooves such as herringbone shape or spiral shape as described above. So-called step bearings, so-called corrugated bearings (stepped to corrugated) formed at intervals may be employed.

In addition, although the lubricating oil was illustrated as the fluid filled in the inside of the fluid bearing apparatuses 101 and 121 in the above description, the fluid which can generate dynamic pressure in each bearing clearance, for example, gas, such as air, magnetic fluid, etc. can also be used. .

In the above, the case where the fluid bearing device 101 according to the present embodiment is assembled to the disk drive spindle motor has been described. However, the fluid bearing device 101 according to the present embodiment rotates at high speed in addition to the spindle motor for information equipment. The present invention can also be preferably used for a motor such as a fan motor that requires high moment rigidity.

FIG. 12 shows a fan motor incorporating a fluid bearing device 101 according to a second embodiment of the present invention, among which a stator coil 104 and a rotor magnet 105 with gaps in a radial (radial direction) interposed therebetween. This example conceptually illustrates an example of a so-called radial gap fan motor in which? In the motor of the illustrated example, the rotor 133 fixed to the upper outer circumference of the shaft member 102 has a wing on its outer circumference, and the bracket 136 achieves its function as a casing for accommodating each component of the motor. Is different from the spindle motor shown in FIG. In addition, since the other structure is similar to the motor shown in FIG. 7, the common reference number is attached | subjected and the duplicate description is abbreviate | omitted.

EMBODIMENT OF THE INVENTION Hereinafter, the fluid bearing apparatus which concerns on 3rd Embodiment of this invention, and the motor provided with this are demonstrated based on FIGS. 13-20.

Fig. 13 conceptually shows an example of the configuration of a spindle motor for information apparatus incorporating a fluid bearing device according to a third embodiment of the present invention. This spindle motor is used for a disk drive device such as an HDD, and is provided with a fluid bearing device 201 for non-contacting support of the rotary body 202 having the shaft member 206 in the radial direction, for example, a radial gap. The drive part 204 which consists of the stator coil 204a and the rotor magnet 204b which faced in the opposite direction, and the bracket 205 are provided. The hub 203 is attached to the shaft member 206, and the rotor magnet 204b is fixed to the hub 203. In addition, the stator coil 204a is fixed to the bracket 205. The housing 210 of the fluid bearing device 201 is fixed to the inner circumference of the bracket 205. As shown in the figure, the hub 203 holds one or a plurality of disks D21 (two in FIG. 13). In the disk drive device configured as described above, when the stator coil 204a is energized, the rotor magnet 204b is rotated by the electromagnetic force generated between the stator coil 204a and the rotor magnet 204b. The disk D21 fixed to 203 rotates integrally with the shaft member 206.

14 shows an example (first configuration example) of the fluid bearing device 201 according to the third embodiment of the present invention. The fluid bearing device 201 shown in the same drawing mainly comprises a rotating member 202 having a bearing member 209 having a plurality of bearing sleeves and a shaft member 206 inserted into an inner circumference of the bearing member 209. It is provided as.

The bearing member 209 is composed of a housing 210 and a plurality of bearing sleeves fixed here in the inner circumference of the housing 210, here a first bearing sleeve 211 and a second bearing sleeve 212.

The housing 210 is formed of, for example, a metal material or a resin material, and is located at both ends of the small diameter plane 210a and the small diameter plane 210a in the axial direction and has a relatively larger diameter than the small diameter plane 210a. It has large diameter surfaces 210b and 210c. On the inner circumference of the small diameter surface 210a, the first bearing sleeve 211 and the second bearing sleeve 212 are arranged along the axial direction. In addition, the large diameter surfaces 210b and 210c are connected to the small diameter surfaces 210a through the stepped surfaces 210d and 210e, respectively.

The shaft member 206 is formed of a metal material such as stainless steel, and has a shaft shape of approximately the same diameter as a whole. On the outer circumferential surface 206a of the shaft member 206, annular seal members 207 and 208 are fixed by appropriate fixing means, for example, by bonding. Therefore, in this structural example, the shaft member 206 which fixed the sealing member 207,208 to the outer periphery, the hub 203 fixed to the shaft member 206, the rotor magnet 204b attached to the hub 203, The rotating body 202 is comprised from the disk D21 and the clamper (not shown) for fixing the disk D21 to the hub 203. In this configuration, the axial center of gravity position of the rotating body 202 in this configuration is above the axial intermediate position of the bearing member 209 (side closer to the hub 203).

When the seal members 207 and 208 are fixed to the shaft member 206, the seal members 207 and 208 protrude from the outer circumferential surface 206a to the outer diameter side and are accommodated inside the housing 210 (inner circumference of the large diameter surfaces 210b and 210c), respectively. . As the fixing means of the seal members 207 and 208 to the shaft member 206, various means such as bonding, pressing, pressing and bonding can be used. The circumferential grooves 206a1 and 206a2 serving as the adhesive reservoir are formed in the outer circumferential surface 206a of the shaft member 206 at which the seal members 207 and 208 are fixed, whereby the seal members 207 and 208 with respect to the shaft member 206 are formed. ), The adhesive strength is improved. The seal members 207 and 208 may be formed of a soft metal material such as brass (brass) or other metal material, or may be formed of a resin material. In addition, one of the sealing members 207 and 208 may be formed integrally with the shaft member 206. As described above, when one seal member is integrally formed with the shaft member, for example, the metal shaft member 206 may be used as an insert part, and either of the seal members may be injection molded with resin.

The outer circumferential surface 207a of the seal member 207 forms a seal volume S21 of a predetermined volume between the large diameter surface 210b of the housing 210, and the outer circumferential surface 208a of the seal member 208 is a lower surface. A seal volume S22 having a predetermined volume is formed between the large diameter surface 210c of the housing 210. In this configuration example, the outer circumferential surface 207a of the seal member 207 and the outer circumferential surface 208a of the seal member 208 respectively form a tapered shape that is gradually reduced toward the outer side of the housing 210. Therefore, the seal spaces S21 and S22 have a tapered shape gradually reduced toward the inner side (the side of the first bearing sleeve 211) of the housing 210.

Among the plurality of bearing sleeves constituting the bearing member 209, the first bearing sleeve 211 is formed in a cylindrical shape with a porous body made of, for example, a sintered metal. In this embodiment, the first bearing sleeve 211 is formed in a cylindrical shape with a porous body of sintered metal mainly composed of copper, and press-fitted, adhered, or press-fitted to the inner circumferential surface (small diameter surface 210a) of the housing 210. It is fixed by such means. In addition, the first bearing sleeve 211 may be formed of a porous body made of a non-metallic material such as resin or ceramic, and may not have an internal hollow other than a porous body such as a sintered metal, or may have a degree of lubricating oil in and out. It may be formed of a material having a structure having only a hollow of size. The same material can be selected also for the 2nd bearing sleeve 212 mentioned later.

On the inner circumferential surface 211a of the first bearing sleeve 211, a plurality of radial bearing surfaces A21 and A22 are formed spaced apart in the axial direction. In this embodiment, as shown, for example in FIG. 15, the area | region (dynamic pressure generation part) which arranged the several dynamic pressure grooves 211a1 in the herringbone shape is formed in the upper radial bearing surface A21, and several dynamic pressure grooves are shown. The area | region (dynamic pressure generation part) which has arrange | positioned 211a2 in the herringbone shape is formed in lower radial bearing surface A22. These radial bearing surfaces A21 and A22 oppose the outer circumferential surface 206a of the shaft member 206, and the first and second lady described later between the outer circumferential surface 206a when the shaft member 206 is rotated. Radial bearing gaps of the radial bearing portions R21 and R22 are formed respectively (see Fig. 14).

Among the plurality of bearing sleeves constituting the bearing member 209, the second bearing sleeve 212 is formed in a cylindrical shape with a porous body made of, for example, a sintered metal, and has an axial one side (here, lower side) of the first bearing sleeve 211. Is placed on. In this embodiment, the second bearing sleeve 212 is formed of a porous body of sintered metal containing copper as a main component, and is cylindrical in shape, and means such as press-fitting, bonding, or press-fitting on the small diameter surface 210a of the housing 210. Is fixed by. Therefore, in this embodiment, the 1st bearing sleeve 211 is arrange | positioned in the area | region of the upper side relatively with respect to the 2nd bearing sleeve 212 in the inner periphery of the housing 210. FIG. Specifically, the radial bearing portions R21 and R22 respectively formed between the radial bearing surfaces A21 and A22 of the first bearing sleeve 211 and the outer circumferential surface 206a of the shaft member 206 opposed thereto are provided. The axial intermediate position is above the axial intermediate position of the bearing member 209 (side closer to the hub 203).

A thrust bearing surface B21 is formed on the entire surface or a partial region of the bottom surface 212b of the second bearing sleeve 212. In this structural example, as shown in FIG. 16, the area | region which arranged the several dynamic pressure grooves 212b1 in the herringbone shape (in other words, arranged the plural dynamic pressure grooves 212b1 which have a bend in the circumferential direction) is formed. do. The thrust bearing surface B21 faces the upper surface 207b of the seal member 207 fixed to the shaft member 206, and the upper surface 207b of the seal member 207 is rotated when the shaft member 206 is rotated. ), A thrust bearing gap of the first thrust bearing portion T21 described later is formed (see FIG. 14).

In addition, a thrust bearing surface C21 is formed on the entire surface or a partial region of the upper surface 211b of the first bearing sleeve 211. In this structural example, as shown, for example in FIG. 17, the area | region which arranged the several dynamic pressure groove | channel 211b1 in the herringbone shape is formed. The thrust bearing surface C21 faces the lower surface 208b of the seal member 208 fixed to the shaft member 206, and the lower surface 208b of the seal member 208 is rotated when the shaft member 206 is rotated. The thrust bearing clearance of the 2nd thrust bearing part T22 mentioned later is formed between () (refer FIG. 14).

Here, the inner diameter dimension (diameter dimension of the inner circumferential surface 212a) of the second bearing sleeve 212 is larger than the inner diameter dimension of the first bearing sleeve 211. Therefore, in the state where the shaft member 206 is inserted into the inner circumference of the 1st bearing sleeve 211 and the 2nd bearing sleeve 212, only the inner peripheral surface 211a of the 1st bearing sleeve 211 is radial bearing surface A21. A22).

A plurality of axial grooves 211d1 and 212d1 are formed on the outer circumferential surfaces 211d and 212d of each of the bearing sleeves 211 and 212 at equal intervals in the circumferential direction, respectively. Thereby, the fluid flow path which can communicate between the thrust bearing parts T21 and T22 formed in the axial direction spaced apart is formed.

The fluid bearing device 201 having the above configuration can be assembled, for example, in the following steps.

First, the first bearing sleeve 211 is adhesively fixed to the small diameter surface 210a of the housing 210. At this time, the upper end surface 211b of the first bearing sleeve 211 is coplanar with the stepped surface 210e of the housing 210 positioned at the outer diameter side thereof, or is axially higher (sealed) than the stepped surface 210e. It is fixed to the small diameter surface 210a in the state where axial positioning was performed so that it might become the side near the bottom surface 208b of the member 208). As a result, only the thrust bearing surface C21 formed on the upper end surface 211b of the first bearing sleeve 211 is provided with the second thrust bearing portion T22 between the lower end surface 208b of the seal member 208. It can be formed.

Next, the second bearing sleeve 212 is introduced into the small diameter surface 210a inner circumference from the lower end side of the housing 210 (axial one side of the first bearing sleeve 211). And the shaft from the lower end surface 212b of the 2nd bearing sleeve 212 which formed the thrust bearing surface B21 to the upper end surface 211b of the 1st bearing sleeve 211 which formed the thrust bearing surface C21. The axial position with respect to the housing 210 of the second bearing sleeve 212 is determined so that the directional separation distance is a predetermined value, and in this position, the second bearing sleeve 212 is replaced by the small diameter surface of the housing 210 ( To 210a). Thereby, the assembly of the bearing member 209 is completed.

In this way, by using both the radial bearing surfaces A21 and A22 collected in one bearing sleeve (first bearing sleeve 211), for example, the radial bearing surfaces (both in the first bearing sleeve 211) are used. The coaxiality between the radial bearing surfaces A21 and A22 of both sides can be completed with high precision only by raising the shaping | molding precision at the time of shaping | molding A21, A22). Therefore, management of coaxiality becomes easy compared with the case where positioning and fixing the radial bearing surfaces A21 and A22 in the other bearing sleeve, respectively, is fixed to the housing 210 like conventionally. Moreover, compared with the case where coaxial matching is carried out between the inner peripheral surface (radial bearing surface) between a some sleeve, the improvement of work efficiency is attained, and a machining cost can be reduced by this.

In this configuration example, the rotating body 202 is relatively compared with the first bearing sleeve 211 having the plurality of radial bearing surfaces A21 and A22 compared with the second bearing sleeve 212 having no radial bearing surface. ) Is placed on the side close to the axial center of gravity position. According to this structure, as described below, the axial directions of the radial bearing portions R21 and R22 formed between the radial bearing surfaces A21 and A22 and the outer circumferential surface 206a of the shaft member 206 opposed thereto are provided. Moment stiffness of the fluid bearing device 201 can be increased by reducing the axial separation distance between the center and the center of gravity of the rotor 202.

In addition, since the two thrust bearing surfaces B21 and C21 are formed in different bearing sleeves in this configuration example, the thrust bearing surfaces B21 and C21 are axially compared with the case where these thrust bearing surfaces B21 and C21 are provided in a single bearing sleeve. The distance between them can be large. Therefore, the moment rigidity can also be improved by such a configuration. In particular, as in this configuration example, the lower end surface 212b as the first end surface located at the one end side (for example, the lower end side) in the axial direction among the end surfaces of the plurality of bearing sleeves 211 and 212, the lower end surface 212b and the shaft By forming the thrust bearing surfaces B21 and C21 on the upper end surface 211b as the second end surface most spaced in the direction, the axial distance between the thrust bearing surfaces B21 and C21 can be made as large as possible. By this, the moment rigidity can be further improved.

In addition, in this configuration example, the second bearing sleeve 212 is brought into contact with the lower end surface 211c of the first bearing sleeve 211 and the upper end surface 212c of the second bearing sleeve 212 opposite thereto. Although the positioning is fixed with respect to the housing 210, it is also possible to positionally fix the 2nd bearing sleeve 212 by the form other than this. For example, assuming a degree of deviation in the axial dimension of the first bearing sleeve 211 and the second bearing sleeve 212, slightly between the two bearing sleeves 211 and 212 (between the lower end face 211c and the upper end face 212c). The axial dimension of both the bearing sleeves 211 and 212 and the axial dimension of the small diameter surface 210a of the housing 210 may be set in advance so that the clearance gap may occur. Of course, it is also possible to first fix the second bearing sleeve 212 to the housing 210 and then fix the first bearing sleeve 211 to the housing 210.

After assembling the bearing member 209 as described above, the shaft member 206 is inserted into the inner circumference of each of the bearing sleeves 211 and 212, and the sealing members 207 and 208 are fixed to the predetermined position of the shaft member 206. do. At this time, each seal member (in the state which managed the axial separation distance from the upper end surface 207b of one seal member 207 to the lower end surface 208b of the other seal member 208 to a predetermined value ( By fixing the 207 and 208 to the shaft member 206, the total sum of the thrust bearing clearances of the thrust bearing portions T21 and T22 described later is set within a predetermined range. In addition, either of the seal members 207 and 208 may be fixed to the shaft member 206 before insertion, or may be integrally formed with the shaft member 206.

After the assembly is completed through the above process, for example, lubricating oil is lubricated as the lubricating fluid in the inner space of the housing 210 which is sealed by the sealing members 207 and 208. Thereby, the inner space of the bearing member 209 including the inner hollow (inner hollow of the porous tissue) of each bearing sleeve 211, 212 is filled with lubricating oil. The filling of the lubricating oil can be performed, for example, by immersing the fluid bearing device 201 in which the assembly is completed in the lubricating oil in a vacuum chamber and then opening it to atmospheric pressure.

Two radial bearing surfaces A21 formed on the inner circumferential surface 211a of the first bearing sleeve 211 when the shaft member 206 (rotator 202) rotates in the fluid bearing device 201 having the above-described configuration. A22 opposes the outer circumferential surface 206a of the shaft member 206 through the radial bearing gap. As the shaft member 206 rotates, the lubricating oil in the radial bearing gap is press-fitted to the axial center side of the dynamic pressure grooves formed in the radial bearing surfaces A21 and A22, respectively, and the pressure thereof rises. The first radial bearing portion R21 and the second radial bearing portion for non-contactingly supporting the shaft member 206 (rotator 202) in the radial direction by the dynamic pressure action of the dynamic pressure grooves 211a1 and 211a2. R22) are configured respectively (see FIG. 14).

At the same time, the thrust bearing clearance between the thrust bearing surface B21 formed in the lower surface 212b of the second bearing sleeve 212 and the upper surface 207b of the sealing member 207 opposite thereto, and the first bearing. On each thrust bearing surface B21, C21 in the thrust bearing clearance gap between the thrust bearing surface C21 formed in the upper surface 211b of the sleeve 211, and the lower surface 208b of the sealing member 208 facing this. An oil film of lubricating oil is formed by the dynamic pressure action of the formed dynamic grooves 212b1 and 211b1, respectively. Then, the first thrust bearing portion T21 and the second thrust bearing portion T22 for non-contactly supporting the shaft member 206 (rotator 202) in both thrust directions by the pressure of these oil films are constituted ( See FIG. 14).

As described above, the seal spaces S21 and S22 formed on the outer circumferential surface 207a side of the seal member 207 and the outer circumferential surface 208a side of the seal member 208 are directed toward the inner side of the housing 210. Since the tapered shape is gradually reduced, the lubricating oil in both seal spaces S21 and S22 is the direction in which the seal space is narrowed by the capturing force by the capillary force and the penetrating action by the centrifugal force during rotation, that is, the housing 210. It is drawn toward the inside. As a result, leakage of lubricant oil from the inside of the housing 210 is effectively prevented. In addition, the seal spaces S21 and S22 have a buffer function for absorbing the volume change amount according to the temperature change of the lubricating oil filled in the internal space of the housing 210, and the oil surface of the lubricating oil is always within the range of the assumed temperature change. It is in seal space S21, S22.

In addition, even when the pressure balance of the lubricating oil is broken due to the presence of the fluid flow path formed by the axial grooves 211d1 and 212d1 of each of the bearing sleeves 211 and 212, such a pressure difference can be quickly resolved, It is possible to prevent the generation of bubbles due to occurrence, the leakage of lubricating oil due to the generation of bubbles, the generation of vibration, and the like. Further, one end of the fluid flow path formed by the axial groove 211d1 of the first bearing sleeve 211 and one end of the fluid flow path formed by the axial groove 212d1 of the second bearing sleeve 212 are respectively. It communicates with the seal spaces S21 and S22 serving as the air opening side. Therefore, even if bubbles are mixed in the lubricant for some reason, the bubbles are discharged to the open air side when circulating along the lubricant, so that the occurrence of the above problems due to the mixing of bubbles can be prevented more reliably.

As mentioned above, although one structural example of the fluid bearing apparatus which concerns on 3rd Embodiment of this invention was demonstrated in detail, this invention is applicable to the fluid bearing apparatus which comprises the structure of that excepting the above without being limited to the said structural example.

In the above, the case where the 1st bearing sleeve 211 is arrange | positioned in the upper region (region of the sealing member 208 side) of the housing 210 relative to the 2nd bearing sleeve 212 in the housing 210 inner periphery is described. Although demonstrated, depending on the position of the axial center of gravity of the rotating body 202, it is also possible to arrange | position on the opposite side (side of the sealing member 207). In other words, the center of gravity of the rotating body 202 is lower than the axially intermediate position of the bearing member 209 (side far from the hub 203), depending on the type of the device in which the fluid bearing device 201 is assembled and used. It is also considered if In this case, the radial bearing portions R21 and R22 are disposed by arranging the first bearing sleeve 211 in the lower region (the region on the seal member 207 side) of the housing 210 relative to the second bearing sleeve 212. By reducing the axial separation distance between the axial center and the center of gravity of the rotor 202, high moment rigidity can be obtained thereby.

In addition, although the case where the 2nd bearing sleeve 212 which does not have a radial bearing surface in the inner periphery was formed separately from the housing 210 was demonstrated, it is also possible to form these integrally. 18 shows an example, and a sleeve-shaped protrusion 210f protruding toward the inner diameter side from the small diameter surface 210a of the housing 210 is formed integrally with the housing 210. In this case, the inner diameter dimension (diameter dimension of the inner circumferential surface 210f1) of the protrusion 210f is larger than the inner diameter dimension of the first bearing sleeve 211. Therefore, in the state which inserted the shaft member 206 (refer FIG. 14) in the inner periphery of the 1st bearing sleeve 211 and the protrusion part 210f of the housing 210, 1st bearing sleeve similarly to the said structural example. Only the inner circumferential surface 211a of 211 can be the radial bearing surfaces A21 and A22. Moreover, the thrust bearing surface B21 of the shape shown, for example in FIG. 16 is formed in the lower surface 210f2 of the protrusion part 210f. In this embodiment, the inner peripheral surface 210f1 of the protrusion 210f and the large diameter surface 210b of the housing 210 are connected through this lower surface 210f2. In this illustrated example, the through hole 210f4 in the axial direction is formed in the protrusion 210f, and the fluid flow path is formed by the through hole 210f4 and the axial groove 211d1.

According to such a structure, while reducing the number of new parts, the assembly process of the bearing member 209 can be performed only by positioning fixing of the first bearing sleeve 211, thereby simplifying the work process. have.

In addition, the bearing member 209 may further have a 3rd bearing sleeve which does not have radial bearing surfaces A21 and A22 in the inner periphery. FIG. 19 shows an example, in which the bearing member 209 includes a housing 210 having a first bearing sleeve 211 and a protrusion 210f as a second bearing sleeve, and a protrusion 210f (second). A third bearing sleeve 213 is further provided on the lower end side of the bearing sleeve). In the same figure, the inner diameter dimension of the protrusion 210f and the inner diameter dimension of the third bearing sleeve 213 are both larger than the inner diameter dimension of the first bearing sleeve 211. Therefore, similarly to the configuration example, only the inner circumferential surface 211a of the first bearing sleeve 211 can be the radial bearing surfaces A21 and A22. In addition, the thrust bearing surface B21 is formed in the lower surface 213b of the third bearing sleeve 213. The outer peripheral surface 213d of the 3rd bearing sleeve 213 is formed with the axial groove 213d1, the through-hole 210f4 of this axial groove 213d1 and the protrusion 210f, and the 1st bearing sleeve 211 The above-mentioned fluid flow path is constituted by the axial grooves 211d1 of ().

This configuration facilitates positioning of the individual bearing sleeves 211 and 213 with respect to the housing 210, and at the same time, any thrust bearing surfaces B21 and C21 are formed of sintered metal, so that lubricants smooth in each bearing gap can be obtained. Can be supplied stably. Therefore, oil fall in a bearing clearance is prevented as much as possible, and high oil film formation ability can be exhibited stably. In addition, as described above, a part of the bearing sleeve is integrally formed with the housing 210 to exert an effect of adjusting the oil amount of the lubricating oil filled in the bearing internal space.

In addition, although the case where the inner peripheral surface of the housing 210 was made into another diameter shape (for example, the small diameter surface 210a and the large diameter surface 210b, 210c) was illustrated, the housing 210 which has a shape other than this is of course illustrated. ) And a bearing member 209 having the same. FIG. 20 shows an example, in which the inner circumferential surface of the housing 210 has a uniform diameter (having a constant inner circumferential surface 210g), whereby the seal members 207 and 208 have a relatively small diameter. The configuration differs from the fluid bearing device 201 shown in 14. In this case, the use of such a housing 210 has the advantage that the shape of the housing 210 can be simplified and further downsized.

In addition, the inner peripheral surface 211a of the 1st bearing sleeve 211 which has the radial bearing surface A21, A22, or thrust bearing surface C21 in the arrangement area | region (dynamic pressure generation part) of dynamic pressure groove 211a1, 211a2 is mentioned above. Although the case was formed in the lower end surface 212b of the 2nd bearing sleeve 212 which has the top surface 211b which has (), or the thrust bearing surface B21, it does not need to be limited to this form. For example, the dynamic pressure generating part which consists of dynamic pressure grooves 211a1, 211a2 may be formed in the outer peripheral surface 206a of the shaft member 206 which opposes each radial bearing surface A21, A22, and also dynamic pressure grooves 212b1, 211b1. The dynamic pressure generating portion may be formed on the upper end surface 207b of the seal member 207 and the lower end surface 208b of the seal member 208 facing the thrust bearing surfaces B21 and C21. Similarly, the dynamic pressure generating part of the form shown below is not limited to the bearing member 209 side, but can be formed in the shaft member 206 and each sealing member 207,208 which oppose this.

In addition, although the structure which generate | occur | produces the dynamic pressure action of a lubricating fluid by the several dynamic pressure groove | channel arranged in the herringbone shape as radial bearing part R21, R22 or thrust bearing part T21, T22 is illustrated above, this invention is demonstrated. Is not limited to this.

For example, as the radial bearing portions R21 and R22, although not shown, a so-called step-shaped dynamic pressure generating portion in which axial grooves are arranged in a plurality of circumferential directions, or a plurality of circular arc surfaces are arranged in the circumferential direction A so-called multi-arc bearing may be employed in which a wedge-shaped radial gap (bearing gap) is formed between the outer circumferential surface 206a of the opposing shaft member 206.

In addition, although one or both of thrust bearing parts T21 and T22 are abbreviate | omitted similarly, the several radial groove shape dynamic pressure groove is formed in the area | region used as thrust bearing surface B21, C21 at predetermined circumferential direction. It can also comprise a so-called step bearing, a corrugated bearing (a stepped wave form), etc. Of course, it is also possible to employ | adopt the spiral shape of the arrangement shape of the dynamic pressure grooves 212b1 and 211b1 in each thrust bearing surface B21 and C21.

In addition, although the structure which the shaft member 206 rotates and supports it with the bearing member 209 was demonstrated above, on the contrary, the bearing member 209 side rotates and supports it at the shaft member 206 side. It is possible to apply this invention also about a structure.

In the above, the lubricating oil is exemplified as a fluid filling the inside of the fluid bearing device 201 and generating a dynamic pressure action of the fluid in the radial bearing gap or the thrust bearing gap. A fluid which can be used, for example, a gas such as air, a lubricant having fluidity such as a magnetic fluid, or a lubricating grease may be used.

Hereinafter, the fluid bearing device which concerns on 4th Embodiment of this invention is demonstrated based on FIGS. 21-31.

FIG. 21 is an impregnated cross-sectional view showing an example (first configuration example) of the fluid bearing device 301 according to the fourth embodiment of the present invention. The fluid bearing device 301 shown in the same drawing is used by being assembled to a spindle motor such as an HDD, for example, and includes a bearing member 305 and a shaft member 303 inserted into the inner circumference of the bearing member 305. The whole 302 is provided as a main structural member. In addition, although it mentions later in detail, the fluid bearing apparatus 301 shown in the same figure is provided with the radial bearing clearance spaced apart in two places of an axial direction, and two radial bearing clearances Cr1 and Cr2 and the area | region between them In this configuration, the gap width is gradually reduced toward the axial direction, respectively.

The rotating body 302 is made of a metal material such as stainless steel, for example, and has a shaft member 303 having a constant diameter over the entire axial length thereof, and a hub (disc hub) provided on the upper periphery of the shaft member 303 ( 304 and also a disk (not shown), a rotor magnet, and a clamper for fixing the disk to the hub 304. The center of gravity (axial center of gravity) G of the rotating body 302 having such a configuration is located on the upper side (side closer to the hub 304) than the axial center of the bearing member 305. The outer circumferential surface 303a of the shaft member 303 is formed into a smooth surface, and the lower end surface 303b is formed into a convex spherical shape.

The bearing member 305 is injection-molded by using a molten material having a bottomed tubular electroforming part 306 made of a precipitated metal formed by electroforming, which will be described later, and the electroforming part 306 as an insertion part. It consists of a coating part 307.

A tapered surface 305c gradually enlarged in the axially upward direction is formed in the upper end opening of the inner circumference of the bearing member 305, and an annular seal space is formed between the tapered surface 305c and the outer peripheral surface 303a of the shaft member 303. (S3) is formed.

In the area of the inner circumferential surface 305a below the tapered surface 305c of the bearing member 305, a region (a thick line region in the figure) serving as the radial bearing surfaces 308 and 309 of the radial bearing portions R31 and R32 is disposed. It is formed in two places apart. As shown in FIG. 22, the radial bearing surfaces 308 and 309 are each provided with the some dynamic pressure groove 308a and 309a arrange | positioned in a herringbone shape as a dynamic pressure generating part. The upper dynamic pressure groove 308a is formed axially asymmetrically with respect to the axial center m of the region between the upper and lower inclined grooves, and the axial dimension X1 of the upper region is greater than that of the lower region. It is larger than the direction dimension X2. On the other hand, the lower dynamic pressure groove 309a is formed axially symmetrically, and the axial dimension of the upper and lower regions is the same as the axial dimension X2, respectively. In this case, at the time of rotation of the shaft member 303, the input force (pumping force) of the lubricating oil by the dynamic pressure groove becomes larger in the upper dynamic pressure groove 308a than in the lower symmetrical dynamic pressure groove 9a. . When the pumping force is not required, the upper dynamic pressure groove 308a may be axially symmetrical like the lower dynamic pressure groove 309a. In addition to the herringbone shape, the dynamic pressure groove may be arranged in a spiral shape or other known shape. In addition, the dynamic pressure groove | channel is abbreviate | omitted in FIG.

A part or whole part annular area | region of the inner bottom surface 305b of the bearing member 305 becomes the thrust bearing surface of the thrust bearing part T3, and in this structure example, this area | region is formed in the smooth plane.

The inner circumferential surface 305a of the bearing member 305 including the radial bearing surfaces 308 and 309 is formed in a tapered shape in which the inner diameter is gradually reduced toward the axially upward direction. That is, in this configuration example, the narrow portion D1 having a small gap width at each upper end of the radial bearing gaps Cr1 and Cr2 formed between the radial bearing surfaces 308 and 309 and the outer peripheral surface 303a of the shaft member 303, Moreover, each lower end part becomes the wide part D2 with a large clearance width. In the illustrated example, the degree of inclination of the inner circumferential surface 305a is exaggerated for ease of understanding, but the gap between the narrow portion D1 and the wide portion D2 of the radial bearing gap Cr1 or Cr2 is shown. The ratio of the reduction amount ε of the radial gap and the axial separation distance (axial length of the radial bearing gap) L between both parts, i.e., the inclination (ε / L), is ε / L≤1 / 500 (with respect to the axis line). Speaking of the inclination angle, it is formed to be very small. Although it is difficult to mass-produce such a taper surface of such a small inclination angle at low cost by general machining, it is possible to mass-produce such a taper surface at low cost and high precision for the reason mentioned later in electroforming.

Next, the manufacturing process of the bearing member 305 of the said structure is demonstrated based on drawing.

The bearing member 305 is a step (Z1) for producing a master, which is a molding mother of the electroforming unit 306, a step (Z2) for masking a part of the master surface with an insulating material, and an electroforming process for the masked master. The step (Z3) of depositing and forming the electroforming unit 306, the step of inserting the master provided with the electroforming unit 306, and injection molding the bearing member 305 (Z4), and the master and electroforming unit It manufactures through the process (Z5) which isolate | separates the bearing member 305 containing 306 in order.

(Z1) master production process

In the master fabrication process shown in Fig. 23A, a solid shaft-shaped master 311 formed of a conductive material such as quenched stainless steel, nickel chromium steel, other nickel alloys, chromium alloys, or the like is formed. In addition to these metal materials, the master 311 may be formed of a non-metallic material such as ceramic on which a conductive treatment (for example, a conductive film is formed on the surface) has been performed.

The molding part N which shape | molds the electroforming part 306 is formed in one area | region of the one end surface of the master 311, and the outer peripheral surface continuous to this. The molding part N has a shape in which the uneven pattern inside the electroforming part 306 is inverted, and die parts for forming hills between the dynamic pressure grooves 308a and 309a in two axially spaced outer peripheral surfaces thereof ( Rows of 311a1 and 311a2 are formed in the circumferential direction. Of course, the shape of the die parts 311a1 and 311a2 may be formed into a spiral shape or the like corresponding to the dynamic pressure groove shape. In addition, the surface precision of the molding part N including the die parts 311a1 and 311a2 directly influences the precision of the electroforming part 306. Therefore, it is preferable that the shaping | molding part N finishes with high precision as possible according to the various precision requested | required of the electroforming part 306.

(Z2) masking process

In the masking step, as shown in FIG. 23B, masking is performed except for the molding portion N of the outer surface of the master 311, so that the masking portion 312 is formed. As the coating material for forming the masking portion 312, a material having insulation and corrosion resistance to an electrolyte solution can be suitably used in consideration of the electroforming process described later.

(Z3) electroforming machining process

In electroforming, the master 311 is immersed in an electrolyte solution containing metal ions such as Ni and Cu, and then energized through the master 311 to deposit the desired metal in the forming portion N of the master 311 ( Electrolytic precipitation). The electrolyte solution may contain a sliding material such as carbon or fluorine particles or a stress relaxation material such as saccharin as necessary. The type of electrodeposited metal is appropriately selected according to physical properties and chemical properties such as hardness and fatigue strength required for the bearing surface.

When electroforming is complete | finished, as shown to FIG. 23C, the electroforming member 313 which deposited the electroforming part 306 is formed in the shaping | molding part N of the master 311. FIG. At this time, the shape of the die parts 311a1 and 311a2 is transferred to the inner circumferential surface of the electroforming part 306, and a plurality of dynamic pressure grooves 308a and 309a shown in FIG. 22 are formed to be spaced apart in the axial direction. In addition, if the thickness of the electroforming part 306 is too thick, the peelability from the master 311 falls, and if too thin, the electroforming part 306 leads to a decrease in durability of the electroforming part 306, so that required bearing performance and bearing size are required. Moreover, it is formed in the thickness of about 10 micrometers-about 200 micrometers depending on an application etc., for example.

Moreover, the electroforming part 306 can also be formed by the method according to the electroless plating (chemical plating) other than the method according to the electroplating (electroplating) mentioned above. When employing a method according to electroless plating, the conductivity of the master 311 and the insulation of the masking portion 312 are not necessary, but the masking portion 312 is preferably formed to have corrosion resistance.

(Z4) insert molding process

Although not shown in the figure, in the insert molding step, the electroforming member 313 is used as an insert component and then placed in a predetermined mold, and then insert molding is performed using a molten material such as molten resin. After injection of the resin, the resin is solidified and the die is opened. As shown in FIG. 24, the electroforming member 313 including the master 311 and the electroforming unit 306 and the coating unit 307 are integrally formed. Molded articles are obtained.

When the coating part 307 is formed from resin, it can be used as a base resin irrespective of crystalline resin and amorphous resin. Examples of the crystalline resins include liquid crystal polymers (LCP), polyphenylene sulfides (PPS), polyether ether ketones (PEEK), polyacetals (POM), polyamides (PA), and the like. Sulfone (PPSU), polyethersulfone (PES), polyetherimide (PEI), polyamideimide (PAI) and the like can be used. The said base resin illustrated can also add 1 type (s) or 2 or more types of fillers, such as a reinforcing material (fiber form, powder form, etc.), a lubricating agent, and an electrically conductive material as needed.

In addition, the coating part 307 can also use molten materials other than resin, for example, low melting metals, such as a magnesium alloy and an aluminum alloy. In addition, so-called MIM molding may be employed by injection molding with a mixture of a metal powder and a binder, followed by degreasing and sintering, and so-called CIM molding using a mixture of a ceramic and a binder can also be used.

Here, in view of the characteristics of electroforming, the start surface of precipitation to the master 311, that is, the inner surface of the electroforming unit 306 becomes a dense surface on which the surface precision of the master 311 (molding unit N) is transferred with high accuracy. The surface on the precipitation end side, that is, the outer surface of the electroforming unit 306 is formed into a rough surface. Therefore, at the time of shaping | molding of the coating | coated part 307, molten resin enters the micro unevenness | corrugation of the surface of the electroforming part 306, and the coupling force of the electroforming part 306 and the coating part 307 is strong by the so-called anchor effect. It becomes one.

(Z5) separation process

The electroforming member 313 formed as described above is transferred to a separation step, and is separated into a bearing member 305 in which the electroforming unit 306 and the covering unit 307 are integrated with the master 311. In this separation process, for example, the inner circumferential surface of the electroforming unit 306 is slightly enlarged by applying an impact to the master 311 or the bearing member 305 to separate the electroforming unit 306 from the surface of the master 311. Thereby, the master 311 becomes separable from the bearing member 305, and when the master 311 is pulled out, the bearing member 305 as a finished product is obtained. As the peeling means of the electroforming unit 306, in addition to the above means, for example, a method or both means by heating (or cooling) the electroforming unit 306 and the master 311 and generating a thermal expansion difference therebetween ( Impact and heating) may be used in combination.

In addition, since the bearing member 305 is formed in a cylindrical shape with a bottom, and the inner circumferential surface 305a is formed in a tapered shape which is gradually reduced toward the opening side, separation of the master 311 from the bearing member 305 is performed. Is called out by force. However, in particular, in the case where the dynamic grooves 308a and 309a are formed in the inner circumferential surface 305a of the bearing member 305 as in the present configuration example, the master 311 is forcibly pulled out of the dynamic pressure grooves 308a and 309a. There is a risk of damaging and further deteriorating bearing performance. On the other hand, in this structural example, as mentioned above, the inclination (epsilon / L) of the inner peripheral surface 305a containing the radial bearing surfaces 308 and 309 of the bearing member 305 is set to about [epsilon] / L <= 1/500. Since the value is set to a small value, the degree of pulling out by force is very small. In addition, since the electroforming part 306 constituting the bearing member 305 is formed with a very thin thickness, and the electroforming part 306 and the cover part 307 are firmly fixed, the master 311 is held. When removing, the electroforming part 306 deforms in accordance with the deformation of the coating part 307 made of resin excellent in elasticity. From the above, damage to the dynamic pressure grooves 308a and 309a due to separation of the master 311 can be effectively prevented.

A lubricating oil as a fluid is inserted into the inner space of the bearing member 305 by inserting the shaft member 303 (rotator 302) prepared separately from the master 311 pulled out on the inner circumference of the bearing member 305 formed as described above. The fluid bearing device 301 shown in FIG. 21 is completed by filling with. On the other hand, since the separated master 311 can be used for repeated electroforming, the high precision bearing member 305 can be mass produced stably and at low cost. When the lubricant is filled, the phosphorus input by the capillary force acts on the lubricant in the seal space S3. As a result, the lubricating oil is always kept within the range of the seal gap S3.

When the shaft member 303 (rotator 302) rotates in the fluid bearing device 301 having the above-described configuration, radial bearing surfaces 308 and 309 spaced apart from two upper and lower portions of the inner circumferential surface 305a of the bearing member 305. Are respectively opposed to the outer circumferential surface 303a of the shaft member 303 through the radial bearing gaps Cr1 and Cr2. As the shaft member 303 rotates, the dynamic pressure of the lubricating oil is generated in the radial bearing gaps Cr1 and Cr2, and the oil film stiffness of the lubricating oil film formed in the radial bearing gaps Cr1 and Cr2 is increased. The shaft member 303 is rotatably supported in a radial direction without contact. As a result, the first radial bearing portion R31 and the second radial bearing portion R32 are formed to rotatably support the rotating body 302 having the shaft member 303 in the radial direction. At the same time, between the lower end surface 303b of the shaft member 303 and the inner bottom surface 305b of the bearing member 305, the rotor 302 having the shaft member 303 is rotatable in the thrust direction. The supporting thrust bearing part T3 is formed.

In general, the rigidity (bearing rigidity) of the oil film formed in the radial bearing gap increases as the gap width decreases. Therefore, in the above structure in which the gap width of the radial bearing gap is gradually reduced toward the axial direction, the oil film stiffness in the narrow width portion D1 having the smaller gap width among the radial bearing gaps is a wide part having a large gap width ( It becomes higher than the oil film rigidity in D2). In this configuration example, since the center of gravity G of the rotating body 302 is located above the axial center of the bearing member 305, the bearing rigidity is increased in the region close to the center of gravity G of the rotating body 302. On the other hand, it is possible to lower the bearing stiffness in the region away from the center of gravity (G). As a result, it is possible to attain the reduction of the bearing rigidity and the low torque required for the rotating body 302 having the shaft member 303 to rotate with high accuracy. In addition, in this structural example, since the said radial bearing clearance gap is formed in two places axially spaced, the bearing center of radial bearing parts R31 and R32 is located above the axial center of the bearing member 305. Done. Therefore, the distance between the bearing center of a radial bearing part and the center of gravity G of the rotating body 302 can be shortened, and it becomes a structure excellent in the load capacity (moment rigidity) with respect to a moment load.

Further, the reduction amount ε of the radial gap between the narrow portion D1 and the wide portion D2 of the radial bearing gap Cr1 or Cr2 described above, and the axial separation distance between the two portions (radial bearing gap) It is preferable that ratio (tilt) ((epsilon / L)) of the axial length of (L) of (1) is 1/1000 <= (epsilon) / L <= 1/500. When the value of the inclination? / L is smaller than 1/1000, it is difficult to sufficiently obtain the effect of improving the bearing rigidity and the effect of reducing the torque. On the other hand, when larger than 1/500, the value of the wide part D2 will become excessive, bearing rigidity may run out, and rotation precision may deteriorate. In addition, when the above-mentioned bearing member 305 is molded, the degree of excessive removal is increased, which may cause damage to the radial bearing surfaces 308 and 309.

Moreover, the minimum diameter gap (inner diameter dimension in narrow part D1) (delta) of radial bearing clearance Cr1 is the ratio (delta / d) with respect to the shaft diameter d of the shaft member 303. It is preferable to form each member so that is 1/1000 <= delta / d <= 1/250, and the reason is described next. First, the lower limit 1/1000 of the ratio δ / d can be derived from the roundness, cylinder degree, etc. of the outer circumferential surface of the master 311 or the shaft member 303 and the inner circumferential surface of the electroforming unit 306. That is, when the diameter gap δ becomes smaller than the roundness and the cylindricality of the outer circumferential surface 303a of the shaft member 303 or the inner circumferential surface 305a of the bearing member 305, between the shaft member 303 and the bearing member 305 Contact occurs and it becomes difficult to secure predetermined performance. Although these various precisions can be made higher, cost increase is inevitable as it becomes higher precision. Therefore, in consideration of the balance between the functional and cost aspects, the ratio δ / d is preferably set to 1/1000 or more. In addition, the upper limit 1/250 of ratio (delta / d) can be derived from a rotation precision or a moment rigidity viewpoint. In other words, when the minimum diameter gap δ of the radial bearing gap becomes large, desired bearing rigidity and moment rigidity cannot be secured, resulting in deterioration of rotational accuracy, contact between the shaft member 303 and the bearing member 305, and the like. Problem occurs. Therefore, it is preferable to make ratio (delta / d) into 1/250 or less.

Moreover, in this structural example, the area | region used as the radial bearing surfaces 308 and 309 of the inner peripheral surface 305a of the bearing member 305, and the inner bottom surface 305b (thrust) which are in sliding contact with the lower surface 303b of the shaft member 303 Bearing surface) is formed in the electroforming portion 306 made of a precipitated metal. In view of the characteristics of the electroforming, the inner surface precision that is the precipitation start surface of the master 311 in the electroforming unit 306 is formed as a dense surface on which the surface shape of the master 311 is transferred with high accuracy. Therefore, if the molded part N which forms the electroforming part 306 is formed with high precision among the outer surface of the master 311, the bearing containing the dynamic pressure grooves 308a and 309a, without performing a separate finishing etc. The precision of the inner peripheral surface 305a and the inner bottom surface 305b of the member 305 becomes high easily, and it becomes possible to manage the width precision of radial bearing clearance Cr1 and Cr2 with high precision. In addition, since the radial bearing surfaces 308 and 309 and the thrust bearing surfaces become metal surfaces, the radial bearing portions R31 and R32 can suppress characteristic changes due to temperature changes and abrasion, and in the thrust bearing portions T3, It can increase wear resistance. In view of the above, it is possible to suppress the increase in the amount of shaking of the rotating body 302 when the fluid bearing device 301 is loaded with vibrations or shocks, and to reduce the deterioration of the rotational performance due to resonance and to maintain high rotational performance. It becomes possible.

As mentioned above, although one structural example of the fluid bearing apparatus which concerns on 4th Embodiment of this invention was demonstrated, the structure of this invention mentioned above is not limited to the fluid bearing apparatus 301 of the said form, The fluid of another form is mentioned. It can also use suitably for a bearing apparatus. Hereinafter, although the structural example is demonstrated based on drawing, the same reference number is attached | subjected about the member and site | part which correspond to the said form for simplicity of description, and the duplicate description is abbreviate | omitted.

25 shows a second configuration example of the fluid bearing device according to the fourth embodiment of the present invention. The difference between the fluid bearing device 321 shown in FIG. 21 and the fluid bearing device 301 shown in FIG. 21 is that the hub 304 constituting the rotating body 302 is mainly provided below the bearing member 305, The center of gravity G of the rotating body 302 is located below the bearing member 305, and correspondingly, the inner diameter dimension of the bearing member 305 is formed to gradually decrease toward the axially downward direction. to be. In addition, although illustration is abbreviate | omitted, the sealing space can also be formed in the opening part of the both ends of the bearing member 305 similarly to the form shown in FIG.

Fig. 26 shows a third configuration example of the fluid bearing device according to the fourth embodiment of the present invention. In the fluid bearing device 331 shown in the figure, the inner peripheral surface of the bearing member 305 is not a tapered shape in which the inner diameter dimension shown in FIGS. 21 and 25 is gradually reduced to either of the axial directions, but a relatively small diameter in the axial direction. Is divided into a first inner circumferential surface 305d and a second inner circumferential surface 305e having a larger diameter than the first inner circumferential surface 305d. A radial bearing surface 308 is formed in a portion or the whole axial region of the first inner circumferential surface 305d, and a radial bearing surface 309 is formed in a portion or the whole axial region of the second inner peripheral surface 305e. It is. That is, in this structural example, the whole radial bearing clearance Cr1 formed between the upper radial bearing surface 308 and the outer peripheral surface 303a of the shaft member 303 becomes narrow part D1, and the lower lady The whole radial bearing clearance Cr2 formed between the ear bearing surface 309 and the outer peripheral surface 303a of the shaft member 303 becomes the wide part D2.

27 shows a fourth configuration example of the fluid bearing device according to the fourth embodiment of the present invention. The fluid bearing device 341 shown in the drawing mainly includes a main body portion 345a having radial bearing surfaces 308 and 309 protruding upward from the main body portion 345a, and a shaft member ( The fluid bearing device 301 shown in FIG. 21 in that it is partitioned by the substantially hemispherical protrusion part 345b which forms the seal space S3 and the lubricating oil storage part 346 between the outer peripheral surface 303a of 303. And configuration is different. As for the side part which comprises the main-body part 345a, the inside diameter dimension is gradually reduced as the whole is axially upward.

Although illustration is abbreviate | omitted, this bearing member 345 can be formed as follows, for example. First, according to the forming procedure of the bearing member 305 mentioned above, the side part and the protrusion part 345b of the main-body part 345a are die-formed in parallel with an axis line, and it isolate | separates from a master. Subsequently, a pressing force is applied from the outer diameter side of the bearing member 345 in a state in which the mold imitated in the shapes of the main body 345a and the protruding portion 345b as a finished product is applied, and the side portion and the protruding portion ( 345b) is deformed in the inner diameter direction to form a kind of plastic deformation state. And when the mold is opened, the bearing member 345 shown in the same figure is obtained.

In the above, the diameter of the radial bearing clearance is different in the axial direction by forming the shaft member 303 with a constant diameter over the entire axial length and by making the inner diameter dimension of the bearing member 305 different in the axial direction. Although the structure mentioned above was demonstrated, in all the structural examples shown above, while the inner peripheral surface 305a of the bearing member 305 formed constant diameter over the axial length, the axial member 303 was axially formed. By using a different diameter, the gap width of the radial bearing gap can be changed in the axial direction.

As mentioned above, although the structure which generate | occur | produces fluid dynamic pressure by the herringbone-shaped or spiral-shaped dynamic pressure groove as radial bearing part R31, R32 is illustrated, this invention is not limited to this. For example, one or both of the radial bearing portions R31 and R32 may be constituted by so-called multi-circular arc bearings or step bearings. These bearings can be obtained by forming a plurality of circular arc surfaces and axial grooves in the radial bearing surfaces 308 and 309 of the bearing member 305 as dynamic pressure generating units. Since the formation method of these dynamic pressure generation parts follows each process at the time of forming dynamic pressure groove 308a, 309a, detailed description is abbreviate | omitted.

FIG. 28 shows an example in the case where one or both of the radial bearing portions R31 and R32 are constituted by a circular arc bearing. In this example, the area | region used as the radial bearing surface 308, 309 of the inner peripheral surface of the bearing member 305 is comprised by the three circular arc surface 351 (so-called three circular arc bearing). The centers of curvature of the three circular arc surfaces 351 are respectively equidistantly offset from the axis center O of the bearing member 305 (shaft member 303). In each area partitioned by three circular arc surfaces 351, the radial bearing gap is a wedge-shaped gap Cr3 gradually reduced to a wedge shape in both circumferential directions. Therefore, when the bearing member 305 and the shaft member 303 rotate relatively, the lubricating oil in a radial bearing clearance is press-fitted to the minimum clearance side of the wedge-shaped clearance Cr3 according to the direction of the relative rotation, and the pressure rises. . By the dynamic pressure action of the lubricating oil, the bearing member 305 and the shaft member 303 are non-contactedly supported. In addition, a deeper axial groove called a separation groove may be formed at the boundary between the three circular arc surfaces 351.

Fig. 29 shows another example in the case where one or both of the radial bearing portions R31 and R32 are constituted by a multi-arc circular bearing. Also in this example, although the area | region used as the radial bearing surface 308,309 of the inner peripheral surface of the bearing member 305 is comprised by three circular arc surfaces 351 (so-called three circular arc bearings), it divides into three circular arc surfaces 351. In each of the regions, the radial bearing gap is a wedge-shaped gap Cr3 gradually reduced to a wedge shape with respect to one direction in the circumferential direction. The multi-arc bearing of such a structure may be called a tapered bearing. Further, a deeper axial groove called a separating groove 352 is formed at the boundary between the three circular arc surfaces 351. Therefore, when the bearing member 305 and the shaft member 303 rotate relatively in the predetermined direction, the lubricating oil in the radial bearing clearance is press-fitted to the minimum clearance side of the wedge-shaped clearance Cr3, and the pressure rises. By the dynamic pressure action of the lubricating oil, the bearing member 305 and the shaft member 303 are non-contactedly supported.

Fig. 30 shows another example in the case where one or both of the radial bearing portions R31 and R32 are constituted by a multi-arc bearing. In this example, in the structure shown in FIG. 29, predetermined area | region (theta) of the minimum clearance side of the three circular arc surfaces 351 respectively centers the axial center O of the bearing member 305 (shaft member 303) with a curvature center. It consists of concentric circular arc surfaces. Therefore, radial bearing clearance (minimum clearance) becomes constant in each predetermined area | region (theta). The multi-arc bearing of such a structure may be called a tapered flat bearing.

31 shows an example in the case where one or both of the radial bearing portions R31 and R32 are constituted by step bearings. In this example, a plurality of axial groove-like dynamic pressure grooves 353 are formed at predetermined intervals in the circumferential direction in an area that becomes the radial bearing surfaces 308 and 309 of the inner circumferential surface of the bearing member 305 (electric casting portion 306). have.

As described above, the radial bearing parts are provided in two axial directions such as the radial bearing parts R31 and R32, but three or more radial bearing parts are disposed over the upper and lower regions of the inner circumferential surface of the bearing member 305. It is good also as an installed structure. In addition, although the multi-arc bearing shown in FIGS. 28-30 is what is called a 3 circular arc bearing, it is not limited to this, Even if it employ | adopts what is called a 4 circular arc bearing, a 5 circular arc bearing, and the circular arc surface which consists of 6 or more circular arc surfaces. good.

In addition, although the case where the dynamic pressure generating part was formed in the radial bearing surfaces 308 and 309 of the electroforming part 306 which comprises the bearing member 305 was illustrated, the shaft member which opposes this radial bearing surface 308 and 309 is illustrated. The dynamic pressure generating portion may be formed on the outer circumferential surface 303a of 303. In this case, the area | regions which become the radial bearing surfaces 308 and 309 of the electroforming part 306 are formed in the cylindrical surface shape without an unevenness | corrugation.

In addition, the dynamic pressure generating part is formed in the radial bearing surface 308, 309 of the electroforming part 306 which comprises the bearing member 305, or the outer peripheral surface 303a of the shaft member 303, and the lady is produced by the dynamic pressure generating part. Although a case was described in which fluid dynamic pressure was generated in the radial bearing gap to configure the radial bearing portions R31 and R32 as dynamic pressure bearings, the radial bearing surfaces 308 and 309 of the electroforming portion 306 were uneven. The radial bearing portions R31 and R32 can also be configured as cylindrical bearings by forming the cylindrical surface shape and forming the outer circumferential surface 303a of the shaft member 303 into a circular cross-sectional shape without irregularities (not shown).

Moreover, although the form which comprises the thrust bearing part T3 with the pivot bearing was demonstrated above, for example, the lower end of the shaft member 303 is made into the flat surface, and this flat surface or the end surface of the bearing member which opposes this is shown. A thrust bearing part can also be comprised by a dynamic pressure bearing by forming several dynamic pressure groove | channel etc. arrange | positioned in a spiral shape or a herringbone shape (not shown).

In addition, although lubricating oil was used as a lubricating fluid to fill the internal space of a fluid bearing apparatus above, the other fluid which can form a fluid film | membrane, for example, lubricating grease, a magnetic fluid, gas, such as air, can also be used.

Since the above-mentioned fluid bearing device is proud of high rotational accuracy, it can be suitably used as a bearing for spindle motors of various motors, for example, disk devices such as HDDs, and fan motors of personal computers that require high rotational performance.

Claims (8)

The bearing sleeve has a radial bearing surface, the shaft member inserted into the inner circumference of the bearing member, and the dynamic pressure action of the fluid generated in the radial bearing gap between the radial bearing surface of the bearing member and the outer circumferential surface of the shaft member. A fluid bearing device having a radial bearing portion for non-contacting support of the shaft member in a radial direction: The bearing sleeve is arranged in plural in the axial direction; And the bearing sleeves are formed with different axial lengths from each other. The convex portion according to claim 1, wherein a convex portion having the same diameter as that of the radial bearing surface is formed on an inner circumferential surface of at least one of the two adjacent bearing sleeves on a bearing sleeve side that is different from the radial bearing surface. Fluid bearing device. 2. The shaft member according to claim 1, wherein the shaft member has a protrusion protruding to the outer diameter side, and the shaft member is non-contacted in the thrust direction by the dynamic pressure action of the fluid generated in the thrust bearing clearance between the end face of the protrusion and the end face of the bearing sleeve. And a thrust bearing portion to be provided. 4. The fluid bearing device according to claim 3, wherein a seal space is formed on an outer circumferential side of the protruding portion. Fluid dynamic pressure in the rotating body having a bearing member, a shaft member inserted into the inner circumference of the bearing member, first and second thrust bearing gaps formed between the bearing member and the rotating body, and the first thrust bearing gaps. In a fluid bearing device having a first dynamic pressure groove region for generating a second dynamic pressure groove region for generating a fluid dynamic pressure in the second thrust bearing gap: The bearing member has two bearing sleeves arranged axially; The two bearing sleeves each have the first dynamic pressure groove region and the second dynamic pressure groove region at both end faces, and the first dynamic pressure groove region of one bearing sleeve faces the first thrust bearing gap, And the second dynamic pressure groove region of the other bearing sleeve faces the second thrust bearing clearance. 6. The fluid bearing device according to claim 5, wherein the first dynamic pressure groove region and the second dynamic pressure groove region are formed in different shapes. 6. A fluid bearing device according to claim 5, wherein a spacer member is sandwiched between said two bearing sleeves. A motor having the fluid bearing device according to any one of claims 1 to 7, a rotor magnet, and a stator coil.

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